Modern techniques of magnetic resonance in the evaluation of primary central nervous system lymphoma: contributions to the diagnosis and differential diagnosis

In addition to findings from conventional magnetic resonance imaging, modern magnetic resonance imaging techniques have provided important information about tumor metabolism, in vivo metabolite formation, water molecule diffusion, microvascular density, and blood-brain barrier permeability, all of which have improved the in vivo diagnostic accuracy of this method in the evaluation of primary central nervous system lymphoma. These nonconventional magnetic resonance techniques are useful in the clinical practice because they enhance conventional magnetic resonance imaging by reinforcing the possibility of a diagnosis and by allowing the early detection of disease recurrence. This report is a review of the most relevant contributions of nonconventional magnetic resonance techniques to the imaging diagnosis of primary central nervous system lymphoma, the differential diagnosis of this disease, and the prognosis of patients. This paper aims to describe a wide range of presentations of primary central nervous system lymphoma, their appearance in imaging, and the differential diagnoses of this disease.

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title: Imaging of lymphoma of the central nervous system, spine, and orbit.
abstract: Lymphomas of the central nervous system, spine, and orbit consist of both systemic lymphomas and primary central nervous system lymphomas. This article addresses the typical imaging findings of lymphoma in both immunocompetent and immunocompromised patients, discusses the differential possibilities, and reviews the response criteria being used in clinical trials. Also described are metabolic imaging techniques with nuclear medicine and advanced MR imaging and how they can help improve the understanding of tumor biology.

title: A New Approach to the Diagnosis and Treatment of Intravascular Lymphoma
abstract: In intravascular lymphoma (IVL) tumor cells are initially restricted to vascular lumina. Neurological syndromes predominate and are caused by ischemia as well as tumor infiltration into the nervous system. Ante mortem diagnosis is challenging and frequently impossible. Chemotherapy is effective if started prior to ischemic damage. Over a three Year period, we have diagnosed IVL in seven patients. Tissue diagnosis could be accomplished in only three cases. For those in whom tissue diagnosis failed we based our diagnosis on clinical presentation, typical magnetic resonance imaging findings, spinal fluid cytopathology, and molecular analyses. Six patients were treated with methotrexate chemotherapy alone or in combination with CHOP. Three patients are in complete remission 9–20 months after initial diagnosis. Another patient achieved a partial response. Two patients died due to progressive disease shortly after initiation of treatment. Grade III toxicity was observed in only 4 of 61 cycles. Based on a small retrospective series of patients, we conclude that methotrexate is a well tolerated and effective agent for the treatment of IVL.

title: An update on primary central nervous system lymphoma.
abstract: The most important recent advance in treatment of primary central nervous system lymphoma has been the introduction of high-dose methotrexate-based chemotherapy. Convincing data demonstrate that the regimens of such chemotherapy improve survival compared with historical controls treated with radiotherapy alone. However, the optical treatment approach is still unclear and therapy can be associated with long-term neurotoxicity. Current research focuses on maximizing survival while minimizing neurologic sequelae.

title: Central Nervous System Lymphoma Characterization by Diffusion‐Weighted Imaging and MR Spectroscopy
abstract: The characterization and differentiation of central nervous system (CNS) lymphoma has important diagnostic, therapeutic, and prognostic significance. The purpose of this study is to characterize the diffusion‐weighted imaging (DWI) and MR spectroscopic (MRS) findings in CNS lymphoma.

title: Percentage Signal Recovery Derived from MR Dynamic Susceptibility Contrast Imaging Is Useful to Differentiate Common Enhancing Malignant Lesions of the Brain
abstract: Differentiation of enhancing malignant lesions on conventional MR imaging can be difficult and various newer imaging techniques have been suggested. Our aim was to evaluate the role of PSR obtained from DSC perfusion measurements in differentiating lymphoma, GBM, and metastases. The effectiveness of PSR was compared with that of rCBV. We hypothesized that the newly defined parameter of PSR is more sensitive and specific in differentiating these lesions.  This retrospective study included 66 patients (39 men and 27 women; age range: 27–82 years) with a pathologically proved diagnosis of primary CNS lymphoma, GBM, or metastases (22 patients in each group). Mean PSR, min PSR, max PSR, and rCBV were calculated. The classification accuracy of these parameters was investigated by using ROC.  Mean PSR was high (113.15 ± 41.59) in lymphoma, intermediate in GBM (78.22 ± 14.27), and low in metastases (53.46 ± 12.87) with a P value < .000. F values obtained from 1-way ANOVA analysis for mean, min, and max PSR ratios were 29.9, 39.4, and 23.4, respectively, which were better than those of rCBV (11.1) in differentiating the 3 groups. Max PSR yielded the best ROC characteristics with an Az of 0.934 (95% CI, 0.877–0.99) in differentiating lymphoma from metastases and GBM. The Az for mean and min PSR of 0.938 (95% CI, 0.0.884–0.990) and 0.938 (95% CI, 0.884–0.991), respectively, was better than rCBV (Az, 0.534; 95% CI, 0.391–0.676) in the differentiation of metastases from GBM and lymphoma (P ≤ .0001).  PSR appears to be a parameter that helps in differentiating intracerebral malignant lesions such as GBM, metastases, and lymphoma.

title: Intraaxial brain masses: MR imaging-based diagnostic strategy--initial experience.
abstract: To develop and retrospectively determine the accuracy of a magnetic resonance (MR) imaging strategy to differentiate intraaxial brain masses, with histologic findings or clinical diagnosis as the reference standard.



The study was HIPAA compliant and was approved by the institutional review board. A waiver of informed consent was obtained. A strategy was developed on the basis of conventional MR imaging, diffusion-weighted MR imaging, perfusion MR imaging, and proton MR spectroscopy to classify intraaxial masses as low-grade primary neoplasms, high-grade primary neoplasms, metastatic neoplasms, abscesses, lymphomas, tumefactive demyelinating lesions (TDLs), or encephalitis. The strategy was evaluated by using data from 111 patients (46 women, 65 men; mean age, 48.9 years) with imaging results available on a departmental picture archiving and communication system from a 5-year search period. Bayesian statistics of the strategy elements and three clinical tasks were calculated.



Search results identified 44 patients with high-grade and 14 with low-grade primary neoplasms, 24 with abscesses, 12 with lymphoma, 11 with TDLs, five with metastases, and one with encephalitis who had undergone conventional and advanced MR imaging. However, only 40 patients (25 women, 15 men; mean age, 45 years) had undergone all studies and had data to allow completion of the entire strategy. Accuracy, sensitivity, and specificity of the strategy, respectively, were 90%, 97%, and 67% for discrimination of neoplastic from nonneoplastic diseases, 90%, 88%, and 100% for discrimination of high-grade from low-grade neoplasms, and 85%, 84%, and 87% for discrimination of high-grade neoplasms and lymphoma from low-grade neoplasms and nonneoplastic diseases.



An integrated MR imaging-based strategy, which is accurate in differentiation of several intraaxial brain masses, was proposed.

title: Central Nervous System Lymphoma: Characteristic Findings on Traditional and Advanced Imaging
abstract: CNS lymphoma consists of 2 major subtypes: secondary CNS involvement by systemic lymphoma and PCNSL. Contrast-enhanced MR imaging is the method of choice for detecting CNS lymphoma. In leptomeningeal CNS lymphoma, representing two-thirds of secondary CNS lymphomas, imaging typically shows leptomeningeal, subependymal, dural, or cranial nerve enhancement. Single or multiple periventricular and/or superficial contrast-enhancing lesions are characteristic of parenchymal CNS lymphoma, representing one-third of secondary CNS lymphomas and almost 100% of PCNSLs. New CT and MR imaging techniques and metabolic imaging have demonstrated characteristic findings in CNS lymphoma, aiding in its differentiation from other CNS lesions. Advanced imaging techniques may, in the future, substantially improve the diagnostic accuracy of imaging, ultimately facilitating a noninvasive method of diagnosis. Furthermore, these imaging techniques may play a pivotal role in planning targeted therapies, prognostication, and monitoring treatment response.

title: Proton magnetic resonance spectroscopy in immunocompetent patients with primary central nervous system lymphoma
abstract: Magnetic resonance spectroscopy imaging (MRSI) non-invasively evaluates the metabolic profile of normal and abnormal brain tissue. Primary central nervous system lymphoma (PCNSL) is a highly aggressive tumor responsive to high-dose methotrexate based regimens. Patients often have complete responses but relapses are common. We characterized the MR spectra of PCNSL patients, correlated MRSI with MRI and evaluated whether early recurrence could be detected by MRSI.Methods: Patients with PCNSL had multi-voxel MRSI before, during, and after treatment. The region of interest was defined using axial FLAIR images. Metabolites assessed were N-acetyl-aspartate (NAA), choline (Cho), creatine (Cr), lipid, and lactate. Ratios of Cho/Cr, NAA/Cho, and NAA/Cr were calculated and correlated with MRI. Overall survival (OS), progression free survival (PFS), and relative risks of each of the ratios were determined. MRSI was performed on 11 men and seven women; median age of 59. Sixty-seven MRSI studies were performed, 17 baseline and 48 follow-up studies. Median ratios in 16 pretreated patients were Cho/Cr-1.90, NAA/Cho-0.39, and NAA/Cr-1.27. Two patients had lipid at baseline, five had lactate and two had both. MRSI correlated with tumor response or progression on MRI; in three patients MRSI suggested disease progression prior to changes on MRI. Univariate analysis of metabolite ratios, lipid, and lactate revealed that none significantly affected PFS or OS. Kaplan–Meier analysis of the presence or absence of lipid, lactate or both revealed a trend for increased PFS.Conclusion: MRSI and MRI correlate with tumor response or progression and may allow early detection of disease recurrence. The presence or absence of lipid and/or lactate may have prognostic significance. Further research using MRSI needs to be done to validate our findings and determine the role of MRSI in PCNSL.

title: Diffusion-Weighted MR Imaging Derived Apparent Diffusion Coefficient Is Predictive of Clinical Outcome in Primary Central Nervous System Lymphoma
abstract: There is evidence that increased tumor cellular density within diagnostic specimens of primary central nervous system lymphoma (PCNSL) may have significant prognostic implications. Because cellular density may influence measurements of apparent diffusion coefficient (ADC) by using diffusion-weighted MR imaging (DWI), we hypothesized that ADC measured from contrast-enhancing regions might correlate with clinical outcome in patients with PCNSL.  PCNSL tumors from 18 immunocompetent patients, treated uniformly with methotrexate-based chemotherapy, were studied with pretherapeutic DWI. Enhancing lesions were diagnosed by pathologic analysis as high-grade B-cell lymphomas. Regions of interest were placed around all enhancing lesions allowing calculation of mean, 25th percentile (ADC25%), and minimum ADC values. Histopathologic tumor cellularity was quantitatively measured in all patients. High and low ADC groups were stratified by the median ADC value of the cohort. The Welch t test assessed differences between groups. The Pearson correlation examined relationships between ADC measurements and tumor cellular density. Single and multivariable survival analysis was performed.  We detected significant intra- and intertumor heterogeneity in ADC measurements. An inverse correlation between cellular density and ADC measurements was observed (P < .05). ADC25% measurements less than the median value of 692 (low ADC group) were associated with significantly shorter progression-free and overall survival. Patients with improved clinical outcome were noted to exhibit a significant decrease in ADC measurements following high-dose methotrexate chemotherapy.  Our study provides evidence that ADC measurements within contrast-enhancing regions of PCNSL tumors may provide noninvasive insight into clinical outcome.

title: Differentiation of toxoplasmosis and lymphoma in AIDS patients by using apparent diffusion coefficients.
abstract: Distinguishing between toxoplasmosis and lymphoma brain lesions in AIDS patients is difficult but clinically relevant. This study was performed to test the hypothesis that diffusion-weighted (DW) imaging with apparent diffusion coefficient (ADC) maps can be used to distinguish these two lesions.



The ADC values were calculated in regions of interest placed in 13 brain toxoplasmosis lesions and eight brain lymphoma lesions in patients with AIDS. These values were compared with those of normal white matter. ADC ratios in lymphoma lesions then were compared with those in toxoplasmosis lesions by using a two-sample two-tailed t test.



Toxoplasmosis lesions demonstrated significantly greater diffusion than that of lymphoma lesions (P =.004). ADC ratios were 1.63 +/- 0.41 (mean +/- standard deviation) in the 13 toxoplasmosis lesions and 1.14 +/- 0.25 in the eight lymphoma lesions. While considerable overlap was present for ADC ratios between 1.0 and 1.6, ADC ratios greater than 1.6 were associated solely with toxoplasmosis, accounting for seven of 13 toxoplasmosis lesions.



ADC values are helpful in differentiating toxoplasmosis from lymphoma in patients with AIDS.

title: Primary Cerebral Lymphoma and Glioblastoma Multiforme: Differences in Diffusion Characteristics Evaluated with Diffusion Tensor Imaging
abstract: Differentiating between primary cerebral lymphoma and glioblastoma multiforme (GBM) based on conventional MR imaging sequences may be impossible. Our hypothesis was that there are significant differences in fractional anisotropy (FA) and apparent diffusion coefficient (ADC) between lymphoma and GBM, which will allow for differentiation between them.  Preoperative diffusion tensor imaging (DTI) was performed in 10 patients with lymphoma and 10 patients with GBM. Regions of interest were placed in only solid-enhancing tumor areas and the contralateral normal-appearing white matter (NAWM) to measure the FA and ADC values. The differences in FA and ADC between lymphoma and GBM, as well as between solid-enhancing areas of each tumor type and contralateral NAWM, were analyzed statistically. Cutoff values of FA, FA ratio, ADC, and ADC ratio for distinguishing lymphomas from GBMs were determined by receiver operating characteristic curve analysis.  FA and ADC values of lymphoma were significantly decreased compared with NAWM. Mean FA, FA ratio, ADC (×10−3 mm2/s), and ADC ratios were 0.140 ± 0.024, 0.25 ± 0.04, 0.630 ± 0.155, and 0.83 ± 0.14 for lymphoma, respectively, and 0.229 ± 0.069, 0.40 ± 0.12, 0.963 ± 0.119, and 1.26 ± 0.13 for GBM, respectively. All of the values were significantly different between lymphomas and GBM. Cutoff values to differentiate lymphomas from GBM were 0.192 for FA, 0.33 for FA ratio, 0.818 for ADC, and 1.06 for ADC ratio.  The FA and ADC of primary cerebral lymphoma were significantly lower than those of GBM. DTI is able to differentiate lymphomas from GBM.

title: Primary central nervous system immunocytoma: MRI and spectroscopy
abstract: We report on a young woman with a primary cerebral immunocytoma. Most primary cerebral nervous system lymphomas (PCNSL) are highly malignant undifferentiated B-cell tumours, there are few data on the clinical course, MRI and spectroscopy findings of this rare PCNSL subtype. MRI revealed a radially enhancing tumour with mild perifocal oedema. MR spectroscopy indicated low cell turnover. Slow clinical progression, no significant changes with treatment, and imaging findings were consistent with a low-grade malignant tumour.

title: Brain lymphoma: usefulness of the magnetic resonance spectroscopy
abstract: The diagnosis of primary central nervous system lymphoma (PCNSL) should always be considered as an emergency because of the therapeutic consequences it implies. In immunocompetent patients, it relies on stereotactic biopsy. Unfortunately, clinical and radiological features may be misleading and delay the diagnostic procedure. The case we report here illustrates the contribution of magnetic resonance spectroscopy in the diagnostic approach of a very atypical PCNSL.

title: How I treat primary CNS lymphoma.
abstract: Primary CNS lymphoma (PCNSL) is a rare malignancy with peculiar clinical and biologic features, aggressive course, and unsatisfactory outcome. It represents a challenge for multidisciplinary clinicians and scientists as therapeutic progress is inhibited by several issues. Molecular and biologic knowledge is incomplete, limiting the identification of new therapeutic targets, and the particular microenvironment of this malignancy, and sanctuary sites where tumor cells grow undisturbed, strongly affects treatment efficacy. Moreover, active treatments are known to be associated with disabling neurotoxicity, posing the dilemma of whether to intensify therapy to improve the cure rate or to de-escalate treatment to avoid sequels. The execution of prospective trials is also difficult because of the rarity of the tumor and the impaired general condition and poor performance status of patients. Thus, level of evidence is low, with consequent uncertainties in therapeutic decisions and lack of consensus on primary endpoints for future trials. Despite this unfavorable background, laboratory and clinical researchers are coordinating efforts to develop new ideas, resulting in the recent publication of studies on PCNSL's biology and molecular mechanisms and of the first international randomized trials. Herein, these important contributions are analyzed to provide recommendations for everyday practice and the rationale for future trials.

title: MRI Findings of Primary CNS Lymphoma in 26 Immunocompetent Patients
abstract: To record the MR imaging features of primary central nervous system lymphoma (PCNSL) and compare these features in monofocal and multifocal disease.  Twenty-one cases of monofocal disease were compared to five cases of multifocal disease. All patients were examined by non-enhanced and contrast-enhanced MRI. Tumor location, tumor size, signal intensity, enhancement characteristics, age distribution, peritumoral edema, cystic changes, and the presence of calcifications were assessed. The MRI features were compared between the monofocal and multifocal disease cases.  The 26 cases, including both the monofocal and multifocal cases, exhibited 37 lesions. Contrast-enhanced images showed variable enhancement patterns: homogeneous enhancement (33 lesions), ring-like enhancement (2), and 'open-ring-like' enhancement (2). The 'notch sign' was noted in four of 33 homogeneously enhancing lesions. One case of hemorrhage and three cases of cystic formation were observed. Intra-tumoral calcification was not found. The frontal lobe, the corpus callosum and the basal ganglia were commonly affected in both the monofocal and multifocal groups. Tumor size differed significantly between the two groups (t = 3.129, p < 0.01) and mildly or moderately enhanced lesions were more frequently found in the monofocal group (p < 0.05). There was no statistical difference between perifocal edema (p > 0.05) and the signal characteristics (p > 0.05) between the two groups.  Our data show that PCNSL has a variable enhancement pattern on MR images. We first reported two lesions with an 'open-ring' enhancement as well as four cases with a 'notch sign'. Monofocal PCNSL cases typically have larger sized tumors with mild or moderate enhancement.

title: Primary central nervous system lymphoma in AIDS: a wider spectrum of CT and MRI findings
abstract: Diagnosis of primary central nervous system lymphoma (PCNSL) in patients with AIDS based on radiological findings is still a challenging problem. Our purpose was to review the CT and MRI findings in PCNSL in our patients with AIDS and compare them with those reported in the literature. CT and MRI of 28 patients with AIDS and pathologically confirmed PCNSL were analysed retrospectively for the number of lesions, their site, size, density, signal intensity, contrast enhancement, oedema and mass effect. We found 82 lesions. On CT 45 lesions were found in 22 patients, whereas MRI revealed 66 in 20 patients. The lymphoma was solitary in 20 patients (29 %) and multiple in 20 (71 %). Spontaneous haemorrhage was seen in 7 patients. Contrast-enhanced MRI showed no enhancement in 27.3 % (18/66) of the lesions. In one patient diffuse signal abnormalities in the white matter were seen on T2-weighted images. Our findings suggest that the previously described spectrum imaging characteristics of PCNSL has widened. Neuroradiologists should be aware of the variable appearance in patients with AIDS. Spontaneous haemorrhage, a nonenhancing lesion, or diffuse white matter changes do not exclude lymphoma in an immunocompromised patient.

title: Posttransplant lymphoproliferative disorder: significance of central nervous system involvement.
abstract: Few data exist regarding central nervous system (CNS) involvement in patients with posttransplant lymphoproliferative disorder (PTLD). The purpose of this study was to review the Israel Penn International Transplant Tumor Registry (IPITTR) experience with CNS involvement by PTLD.



Nine hundred ten PTLD cases from the United States were reported to the IPITTR and reviewed for CNS involvement.



One hundred thirty-six transplant recipients with PTLD (15%) had CNS involvement. The highest incidence of CNS involvement occurred in pancreas (3 of 11; 27%) and kidney transplant recipients (76 of 429; 18%). Fifteen cases occurred in children and 121 cases in adults. For both children and adults, isolated CNS disease was associated with better survival when compared with multiple-site involvement (children: 29% vs 0%; adults: 12% vs 6%; P < .05). Three-year survival in PTLD patients with CNS involvement was 9.4% and without CNS involvement was 49.4% (P < .01). Radiation therapy alone appeared to provide the best survival rates (25%).



CNS involvement in transplant recipients with PTLD carries an ominous prognosis; however, isolated CNS involvement has a better prognosis than CNS plus extracranial involvement. Radiation therapy alone provides the best results, but this may be a reflection of isolated CNS disease.

title: Primary central nervous system post‐transplantation lymphoproliferative disorder
abstract: Primary central nervous system (CNS) post‐transplantation lymphoproliferative disorder (PCNS‐PTLD) is a rare complication of solid organ transplantation. The objectives of this study were to define the clinical, radiologic, and pathologic features of this disease and to explore the impact of treatment on patient outcomes.

title: Neurologic complications after solid organ transplantation
abstract: Neurologic complications are common after solid organ transplantation and are associated with significant morbidity. Approximately one‐third of transplant recipients experiences neurologic alterations with incidence ranging from 10% to 59%. The complications can be divided into such of those common to all types of transplant and others of those specific to transplanted organ. The most common complication seen with all types of transplanted organ is neurotoxicity attributable to immunosuppressive drugs, followed by seizures, opportunistic central nervous system (CNS) infections, cardiovascular events, encephalopathy and de novo CNS neoplasms. Amongst immunosuppressants, calcineurin inhibitors are the main drugs involved in neurotoxicity, leading to complications which ranges from mild symptoms, such as tremors and paresthesia to severe symptoms, such as disabling pain syndrome and leukoencephalopathy. Neurologic complications of liver transplantation are more common than that of other solid organ transplants (13–47%); encephalopathy is the most common CNS complication, followed by seizures; however, central pontine myelinolysis can appear in 1–8% of the patients leading to permanent disabilities or death. In kidney transplanted patients, stroke is the most common neurologic complication, whereas cerebral infarction and bleeding are more typical after heart transplantation. Metabolic, electrolyte and infectious anomalies represent common risk factors; however, identification of specific causes and early diagnosis are still difficult, because of patient’s poor clinical status and concomitant systemic and metabolic disorders, which may obscure symptoms.

title: Primary dural lymphomas: a review.
abstract: Primary dural lymphoma (PDL) is a rare subtype of primary central nervous system lymphoma (PCNSL) that arises from the dura mater and differs biologically from other CNS lymphomas. The PDL is usually a low-grade marginal zone lymphoma (MZL), whereas other types of PCNSLs are usually high-grade, diffuse, large B-cell lymphomas. A PDL usually presents with single or multiple extraaxial masses that enhance diffusely with addition of contrast material and can be confused with meningioma. The MZLs respond well to local therapy such as surgery and radiation treatment. Most patients attain complete response and have good local disease control. Nevertheless, the risk of systemic relapse appears to be high, probably because the dura mater is outside of the blood-brain barrier.

title: Primary Dural Mucosa-Associated Lymphoid Tissue-Type Lymphoma: Case Report and Review of the Literature
abstract: A 47-year-old Hispanic male presented with visual field disturbances, memory impairment, and a seizure. CT and MRI were consistent with meningioma. Both neurologic exam and routine laboratory tests were within normal limits. The patient underwent craniotomy and subtotal resection of the tumor. On H&E, the lesion was composed of a lymphoid mass with well-defined irregularly shaped follicles surrounded by a monomorphic population of small lymphocytes. Marginal zones stained for B-cell markers, CD20 and CD79a, one T-cell marker, CD43, and kappa light chains. While other markers did not stain the majority of tumor cells, they did identify other lymphoid and plasma cell elements. A diagnosis of marginal zone B-cell lymphoma of dura, mucosa-associated lymphoid tissue (MALT)-type (extranodal) was made. MALT-type lymphomas are unusual in the nervous system; this is the first such case reported in a male and serves to emphasize the wide diversity of presentation of a neoplasm originally described in the GI tract and thus far described in the CNS only in females.

title: MALT lymphoma presenting as a meningioma
abstract: A 50-year-old man with no significant past medical history was admitted for progressive left hearing loss with recent onset of diplopia, right facial palsy and mild gait ataxia. Magnetic resonance imaging revealed an extraaxial tumor in the left cerebellopontine angle. The mass was isointense on all sequences, and displayed homogeneous enhancement with gadolinium suggesting a meningioma . The patient underwent a biopsy. Pathologic analysis disclosed a B-lymphoid tissue proliferation corresponding to a MALT lymphoma (mucosaassociated lymphoma)  . Staging showed

title: Cranial vault lymphoma: a systematic review of five patients
abstract: Bone involvement is a common finding in many types of lymphoma (Clin Oncol 9(3): 195–196, 1997). However, cranial vault affliction has been regarded as an exceedingly rare presentation, particularly in the case of primary lymphoma (J Neurosurg 108(5): 1018–1020, 2008). Our objective is to describe a series of five immunocompetent patients with histologically confirmed cranial vault lymphoma (CVL), and to conduct a systematic review of the current literature. Our review points out identical imaging patterns in most of the lesions for all reported CVL cases, despite their different histological subtypes. This typical pattern can be seen on computed tomography (CT) scans and magnetic resonance imaging (MRI) as an expansive tumor that affects all three compartments of the cranial vault, including the scalp, skull bone, and pachymeninges, even in the absence of osteolysis. We argue that the absence of osteolysis might enhance diagnostic capability. In the appropriate clinical setting, these features represent important disease characteristics that may help with an earlier diagnosis. Large B-cell lymphoma was the most common subtype of primary CVL.

title: Primary central nervous system lymphomas (PCNSL): MRI features at presentation in 100 patients
abstract: To avoid an unnecessary extend of surgery in primary central nervous system lymphoma (PCNSL), the diagnosis should be suspected after MRI.Pre-treatment MRI examinations of 100 immunologically competent patients with biopsy-proven PCNSL were evaluated. All patients had T2- and T1-weighted images with contrast enhancement. Diffusion-weighted MRI (DW-MRI) was available in 15, proton-MR-spectroscopy (1H-MRS) in four patients.The number of lesions ranged from one (n=65 patients) to eight (n=1) with a mean of 1.7. The most frequent locations were the cerebral hemispheres (n=66), the basal ganglia (n=27) and the corpus callosum (n=24). In the 65 patients with a solitary lesion, hemispheric lesions were most frequent (n=23) followed by corpus callosum (n=18). Contrast enhancement was found in all but one patient. 1H-MRS revealed a uniformly pathologic pattern of metabolite concentrations in all patients.Characteristic imaging features of PCNSL are contrast-enhancing lesions with a diameter of at least 15 mm in contact with the subarachnoid space. DW-MRI and proton spectroscopy may aid in differential diagnosis.

title: Non-enhancing primary CNS lymphoma
abstract: Primary central system lymphomas (PCNSL) are highly proliferative tumors that require aggressive treatment, e.g. using high-dose methotrexate-based chemotherapy. Early histological diagnosis is crucial for proper management of PCNSL. Histological diagnosis is obtained through stereotactic biopsy which is usually performed upon demonstration of the typical hallmarks of PCNSL on MRI. This includes large, preferentially periventricular, homogenously contrast-enhancing lesions . Although the MRI presentation of PCNSL is relatively uniform regarding the appearance as homogenously contrast-enhancing lesion(s), the MRI presentation of PCNSL may very rarely be atypical [2, 3] and may lead to significant delay in diagnosis and therapy initiation in such patients. We here present a patient with the rare case of a PCNSL without contrastenhancement. An 81-year-old patient presented with a 5-week history of rapidly progressive dementia. On examination, he was disoriented and showed psychomotor slowing and gait difficulty. The Mini Mental state examination (MMSE) revealed 16/30 points. He was HIV negative and all serological and biochemical tests were normal. The CSF examination showed just a slight increase in protein content (556 mg/l), no pleocytosis and no atypical cells. The MRI of the brain taken without prior steroid treatment revealed diffuse white matter changes involving both hemispheres. No pathological contrast-enhancement could be detected . A diagnosis of gliomatosis cerebri was initially suspected. A biopsy was taken from the right frontal lobe. Histological examination revealed a diffuse large cell lymphoma (non-Hodgkin’s lymphoma of germinal B cell origin; . The present case highlights the fact that, in very rare cases, PCNSL may present as a non-enhancing lesion. Non-enhancing presentation was found in 1% of patients in a large series of immunocompetent patients  and is just one form of atypical MRI presentation of PCNSL. Another atypical form is the presentation with a central nonenhancing necrosis; this is found in 6–17% of immunocompetent PCNSL patients . PCNSL without contrast uptake are usually caused by angiotropic large cell lymphoma or intravascular lymphomatosis . In contrast, the present case did not show a particular angiotropic pattern but had the typical pattern of a diffuse large cell lymphoma with some perivascular accentuation . Unusual non-enhancing presentation may lead to substantial prolongation of definitive diagnosis and start of therapy. This underlines that PCNSL without contrast-enhancement has to be kept in the differential diagnosis of diffuse white matter disorders. Also, it further supports the importance of histologic verification before the onset of therapy. Since histological diagnosis of PCNSL may be greatly hampered by the use of lympholytic steroids prior to biopsy, it M. L. Lachenmayer and E. Blasius contributed equally.

title: Non-enhancing relapse of a primary CNS lymphoma with multiple diffusion-restricted lesions
abstract: Primary CNS lymphoma (PCNSL) and its variant primary intraocular lymphoma (PIOL) are rare forms of extranodal non-Hodgkin’s lymphoma confined to the CNS including the retina and the optical nerve; histologically, most cases are diffuse large B cell lymphomas. PCNSL in immunocompetent patients display typical radiological features on MRI, i.e. intensely and homogeneously enhancing lesions with moderate edema. Here, we report a 52-year-old male with a history of a PIOL and two consecutive intracerebral relapses who presented with dysarthria, dysphagia, and gait ataxia. Gadolinium-enhanced T1 scans were unremarkable but multiple lesions with restricted water diffusivity were seen on diffusion-weighted imaging. Relapse of his PCNSL was secured histologically only on autopsy. The possible etiology of the diffusion-restricted lesions is discussed.

title: [Lymphomatosis cerebri as the cause of leukoencephalopathy].
abstract: Lymphomatosis cerebri (LC) is an infrequent type of primary lymphoma of the central nervous system that is characterised by diffuse, infiltrating involvement of the white matter of the brain without the formation of a mass.



To report the case of a patient with LC in order to draw attention to this disease, which is rarely diagnosed, and to its initial presentation in magnetic resonance imaging (MRI) as leukoencephalopathy.



Our patient was a 56-year-old female who had clinical signs and symptoms of sub-acute dementia. Computerised axial tomography and MRI of the head revealed extensive, diffuse and bilateral involvement of the white matter, basal nuclei, mesencephalon and pons, with no mass effect or contrast enhancement. A stereotactic biopsy of the white matter (which was not conclusive) showed a perivascular mixed mononuclear-cell inflammatory infiltrate of B and T cells. No cytologic atypia was observed. Treatment was established with corticoids, which produced a clinical and radiological improvement in the first two months. During the next month the patient underwent rapid clinical deterioration with sleepiness and a worsening of the ability to walk. In an MRI scan the lesion had a more heterogeneous appearance with mass effect on adjacent structures and patchy contrast enhancement. A wedge biopsy of brain tissue led to a diagnosis of high-grade B-cell lymphoma.



The imaging and histological appearance of LC may not be the one typically found in primary lymphomas of the central nervous system, and its clinical presentation may be similar to that of other diffuse processes involving compromise of the white matter (cerebral gliomatosis, inflammatory diseases of the white matter, such as Behçet's disease, Sjögren's disease or systemic lupus erythematosus).

title: Intravascular lymphomatosis presenting as posterior leukoencephalopathy.
abstract: 73-YEAR-OLD woman presented with progressive confusion overa5-weekperiod, after having become increasingly apathetic for the past several months and having lost 22.5 kg over the past 1 year. On examination, the patient was normotensive and cachectic. Neurologically, there was psychomotor retardation with disorientation to place and time, complete visual loss except for a small preserved central focus, and denial for the degree of visual loss.

title: The neurological masquerade of intravascular lymphomatosis.
abstract: Intravascular lymphomatosis (IVL) is an uncommon systemic disease characterized by occlusion of small vessels by malignant lymphomatous cells. Central nervous system involvement usually presents as subacute encephalopathy, dementia, seizures, or multifocal cerebrovascular events.



To increase awareness about IVL, an uncommon cause of neurological disease.



This is a retrospective case series of 8 pathologically proved cases of IVL with neurological disease. Patients were part of a pathological series collected between April 1962 and October 1998 at Indiana University School of Medicine and the Armed Forces Institute of Pathology, Washington, DC.



Neurological and neuropathological examinations were performed at tertiary referral hospitals.



Eleven patients were diagnosed pathologically as having IVL, but 3 were not included in this evaluation because of a lack of appropriate clinical information. Of the final sample (n = 8), there were 4 men and 4 women (mean +/- SD age, 62.9 +/- 9.9 years).



All 8 patients had focal neurological deficits, 7 had encephalopathy or dementia, 5 had epileptic seizures, and 2 had myelopathy. Death occurred at a mean of 7.7 months (range, 1-24 months) after the onset of symptoms. All patients had elevated cerebrospinal fluid protein levels, 4 had pleocytosis, and 2 had an elevated IgG level in their cerebrospinal fluid. Of the 4 patients who underwent a brain biopsy, 1 was diagnosed as having IVL before death.



Intravascular lymphomatosis is an uncommon disease with a myriad of potential neurological manifestations. Diagnosis requires a high index of suspicion and a pathological examination. If diagnosed early, aggressive chemotherapy is potentially curative, although the overall prognosis remains dismal.

title: Angiotropic large cell lymphoma with imaging characteristics of CNS vasculitis.
abstract: This report documents a case of angiotropic large cell lymphoma (ALCL) with imaging characteristics of CNS vasculitis. A 47-year-old man was unresponsive after a 5-month progression of neurologic deterioration and intermittent fevers. MR imaging revealed multiple areas of abnormally increased T2 signal intensity in the cerebral cortex and subcortical white matter. Despite corticosteroid treatment for presumed CNS vasculitis, the patient died. Necropsy revealed a diffuse intravascular malignant mononuclear proliferation consistent with ALCL.

title: Neurological presentation of intravascular lymphoma: report of two cases and discussion of diagnostic challenges
abstract: About a third of patients with intravascular lymphoma (IVL) present to the neurologist with symptoms mimicking thromboembolic events. Diagnosis is difficult, and often made postmortem. As remission may be induced in almost half of patients with combination chemotherapy, early diagnosis of this rare disease is essential. We report two cases of IVL. A 62‐year‐old male presented with hyperacute myelopathy followed by cortical ischaemic events. The diagnosis was reached with frontal cortical and meningeal biopsy. A 56‐year‐old female had symptoms of transient ischaemic events, subacute dementia, weight loss and fever. As the disease progressed, she developed nephrotic syndrome and thrombocytopenia. Diagnosis was made postmortem. Our cases illustrate that IVL should be considered in the differential diagnosis of cerebral and systemic vasculitis and subacute bacterial endocarditis. Literature suggests IVL can also mimic Creutzfeld–Jakob disease and paraneoplastic encephalomyelitis.

title: A 62-year-old man with fluctuating neurological deficits and skin lesions.
abstract: A 62-year-old man with no significant medical history experienced fatigue, night sweats, hoarseness of voice, and dry cough, which were followed by vision disturbances in his left eye. He lost about 4.5 kg (10 lb) in just over a month. Three weeks later, he had difficulty recollecting his e-mail password and trouble with word finding. The next day, he experienced numbness in his left arm. He also developed a maculopapular and erythematous rash in the groin, genitalia, and buttocks. The results of an initial neurological examination were normal, including his higher mental functions. An initial blood workup revealed normocytic normochromic anemia. The results of cerebrospinal fluid studies were unremarkable. Magnetic resonance imaging of his brain at hospital admission revealed multifocal increased T2 signals in the subcortical white matter. A conventional cerebral angiogram was unremarkable. A biopsy specimen from the right frontal lobe revealed demyelination and perivascular lymphocytic infiltration. A provisional diagnosis of acute disseminated encephalomyelitis was made. In spite of steroid treatment and plasmapheresis, his clinical status deteriorated rapidly. The approach to the diagnosis of a rapidly progressive multifocal brain disorder is discussed.

title: Ocular Adnexal Lymphomas: A Review
abstract: Ocular adnexal lymphomas comprise 1% to 2% of all non-Hodgkin lymphomas and about 8% of extranodal lymphomas. They are a heterogeneous group of malignancies, the majority of which are primary extranodal lymphoma with most (up to 80%) of the marginal zone of mucosa associated lymphoid tissue type (MALT lymphoma). This review will encompass the incidence, histology, immunophenotyping, recent advances in molecular and cytogenetics, clinical features including outcome, and prognostic factors. The association with Chlamydia psittaci and the very recently recognized occurrence in the context of IgG4-related sclerosing disease will be discussed. Finally, traditional (surgery, radiotherapy, chemotherapy) and newer forms of therapy (immunotherapy and radioimmunotherapy) will be reviewed.

title: The differentiation of idiopathic inflammatory pseudotumor from lymphoid tumors of orbit: Analysis of 319 cases
abstract: To analyze the clinical, morphologic, immunophenotypic, and molecular genetic differences between idiopathic inflammatory pseudotumor and lymphoid tumors of the orbit.  209 patients with IOIP and 110 patients with lymphoid tumors seen between January 1, 1978 and December 31, 1999 in Zhongshan Ophthalmic Center, Sun Yat-sen University were evaluated retrospectively.  More patients with lymphoid tumors had palpable mass than patients with idiopathic orbital inflammatory pseudotumor (IOIP) (P < 0.0001), with the percentage of 90% and 65%, respectively, whereas more patients with IOIP had swollen eyelid, eyelid or conjunctival congestion, pain, retinal folds or hamorrhage, and optic nerve atrophy than patients with lymphoid tumors, with the percentage of 55% and 40% (P = 0.014), 42% and 24% (P = 0.001), 24% and 1% (P < 0.0001), 14% and 4% (P = 0.004), 7% and 2% (P = 0.043), respectively. Ultrasound and computed tomography/magnetic resonance image (CT/MRI) scan usually could not differentiate IOIP from lymphoma. Nearly one third of patients with IOIP could not be easily differentiated pathologically from lymphoid tumor. Immunophenotypic, and molecular genetic analyses can differentiate IOIP from lymphoid tumor based on polyclonal or monoclonal proliferation of lymphocytes with the IOIP being polyclonal and lymphoma monoclonal.  Idiopathic orbital inflammatory pseudotumor and lymphoid tumor showed distinguishing clinical, morphologic, immunophenotypic, and molecular genetic characteristics.

title: Orbital Masses: the Usefulness of Diffusion-Weighted Imaging in Lesion Categorization
abstract: IntroductionDiffusion-weighted imaging (DWI) produces contrast among different kinds of tissues according to their diffusibility characteristics. The purpose of our study was to evaluate the role of DWI including measurement of apparent diffusion coefficient (ADC) values in recognizing benignancy or malignancy of orbital masses. total of 39 orbital masses were evaluated visually for signal characteristics on DWI and ADC maps. ADC values were calculated for each lesion. Visual signal characteristics were compared using the Fisher exact test. Receiver operating characteristic (ROC) analysis was carried out to determine sensitivity and specificity for distinguishing malignant from benign lesions using ADC values. The Mann–Whitney U test was applied to compare the ADC values between orbital lymphomas and idiopathic orbital inflammatory (IOI) lesions, and between optic nerve sheath meningiomas and gliomas.ResultsVisual assessment revealed no significant difference between benign and malignant lesions on DWI (p-value = 0.66). However, visual assessment of ADC maps revealed a statistically significant (p-value ≤ 0.0001) between benign and malignant lesions. ROC analysis showed a sensitivity of 83.33 % and a specificity of 85.71 % when using an optimal cut off ADC value of 0.84 × 10−3 mm2/s for differentiating malignant from benign lesions. Significant differences in mean ADC values were observed between lymphomas and IOI lesions (p-value = 0.05), and between optic nerve sheath meningiomas and gliomas (p-value = 0.03).ConclusionDWI is useful for differentiating malignant and benign orbital tumors if accompanied by visual assessment of ADC maps and ADC value calculations.

title: Diffusion-Weighted Imaging of Orbital Masses: Multi-Institutional Data Support a 2-ADC Threshold Model to Categorize Lesions as Benign, Malignant, or Indeterminate
abstract: DWI has been increasingly used to characterize orbital masses and provides quantitative information in the form of the ADC, but studies of DWI of orbital masses have shown a range of reported sensitivities, specificities, and optimal threshold ADC values for distinguishing benign from malignant lesions. Our goal was to determine the optimal use of DWI for imaging orbital masses through aggregation of data from multiple centers.  Source data from 3 previous studies of orbital mass DWI were aggregated, and additional published data points were gathered. Receiver operating characteristic analysis was performed to determine the sensitivity, specificity, and optimal ADC thresholds for distinguishing benign from malignant masses.  There was no single ADC threshold that characterized orbital masses as benign or malignant with high sensitivity and specificity. An ADC of less than 0.93 × 10−3 mm2/s was more than 90% specific for malignancy, and an ADC of less than 1.35 × 10−3 mm2/s was more than 90% sensitive for malignancy. With these 2 thresholds, 33% of this cohort could be characterized as “likely malignant,” 29% as “likely benign,” and 38% as “indeterminate.”  No single ADC threshold is highly sensitive and specific for characterizing orbital masses as benign or malignant. If we used 2 thresholds to divide these lesions into 3 categories, however, a majority of orbital masses can be characterized with >90% confidence.

title: Orbital lymphoma: imaging features and differential diagnosis
abstract: PurposePatterns of orbital lymphoma at diagnosis and follow-up are described. We also discuss differential diagnosis of orbital masses.Materials and methodsThis pictorial review contains 19 cases of orbital lymphoma before and after treatment. Superior-lateral quadrant and extra-conal location were observed predominantly. Effective response after treatment was presented on follow-up imaging, although few local relapses were found. Further follow-up showed no changes of residual images.DiscussionLocation of orbital masses can help in the differential diagnosis. Moreover, imaging features of lymphoma at diagnosis can be useful in planning surgical biopsy. Pattern of follow-up described may be relevant on monitoring imaging.Teaching points• Orbital lymphoma involves mainly superior-lateral quadrant and the orbital structures inside.• Location of retrobulbar mass-like lesions are useful information in the differential diagnosis.• Satisfactory response is detected after treatment, however relapse is noted, so follow-up is needed.

title: Clinicopathological features of neuropathy associated with lymphoma.
abstract: Lymphoma causes various neurological manifestations that might affect any part of the nervous system and occur at any stage of the disease. The peripheral nervous system is one of the major constituents of the neurological involvement of lymphoma. In this study we characterized the clinical, electrophysiological and histopathological features of 32 patients with neuropathy associated with non-Hodgkin's lymphoma that were unrelated to complications resulting from treatment for lymphoma. Nine patients had pathologically-proven neurolymphomatosis with direct invasion of lymphoma cells into the peripheral nervous system. These patients showed lymphomatous cell invasion that was more prominent in the proximal portions of the nerve trunk and that induced demyelination without macrophage invasion and subsequent axonal degeneration in the portion distal from the demyelination site. Six other patients were also considered to have neurolymphomatosis because these patients showed positive signals along the peripheral nerve on fluorodeoxyglucose positron emission tomography imaging. Spontaneous pain can significantly disrupt daily activities, as frequently reported in patients diagnosed with neurolymphomatosis. In contrast, five patients were considered to have paraneoplastic neuropathy because primary peripheral nerve lesions were observed without the invasion of lymphomatous cells, with three patients showing features compatible with chronic inflammatory demyelinating polyneuropathy, one patient showing sensory ganglionopathy, and one patient showing vasculitic neuropathy. Of the other 12 patients, 10 presented with multiple mononeuropathies. These patients showed clinical and electrophysiological features similar to those of neurolymphomatosis rather than paraneoplastic neuropathy. Electrophysiological findings suggestive of demyelination were frequently observed, even in patients with neurolymphomatosis. Eleven of the 32 patients, including five patients with neurolymphomatosis, fulfilled the European Federation of Neurological Societies/Peripheral Nerve Society electrodiagnostic criteria of definite chronic inflammatory demyelinating polyneuropathy. Some of these patients, even those with neurolymphomatosis, responded initially to immunomodulatory treatments, including the administration of intravenous immunoglobulin and steroids. Patients with lymphoma exhibit various neuropathic patterns, but neurolymphomatosis is the major cause of neuropathy. Misdiagnoses of neurolymphomatosis as chronic inflammatory demyelinating polyneuropathy are frequent due to a presence of a demyelinating pattern and the initial response to immunomodulatory treatments. The possibility of the concomitance of lymphoma should be considered in various types of neuropathy, even if the diagnostic criteria of chronic inflammatory demyelinating polyneuropathy are met, particularly in patients complaining of pain.

title: Hypertrophy of the nerve roots of the cauda equina as a paraneoplastic manifestation of lymphoma.
abstract: HYPERTROPHYOFTHE caudaequinanerve rootsisanonspecific finding and may be seen in hereditary andacquireddemyelinatingneuropathiesorduetoinfiltrationofthenerve rootsbymalignancy.Wedescribeapatient with hypertrophy of the cauda equinanerverootsasalikelyparaneoplastic phenomenon. A60-year-oldmanwasseenfora 3-year history of progressive distal lower limb paresthesias. For 18 monthsbeforehisevaluation,hehad beensymptomaticwithgaitdifficulty thatwouldincreaseinthedark.Walking for prolonged distances was accompanied by leg weakness, heaviness, and numbness, all of which wouldimproveonsittingdown.On examination,hehadmildweakness ofthedistalaspectofthelowerlimb muscles with marked loss of vibrationandmoderatelossofpositionperceptioninthetoes.Perceptionoflight touchandpinprickwereintact.His lower limb reflexes were absent, he hadaflexorplantarresponse,andhe haddifficultywalkingonhistoesor heels.Hehadpositiveresultsforthe Romberg sign. Nerve conduction studies showed evidence of a mild, length-dependent,axonalperipheral neuropathy.Somatosensoryevoked potentialstudieswereremarkablefor impaired conduction in the central proprioceptive pathways below the cervical level. Cerebrospinal fluid analysis revealed a protein level of 0.138 g/dL (reference range, 0.0140.045g/dL),anormalglucoselevel, andabsenceofincreasedcellularity. Diffuseabnormalthickeningand enhancement of the cauda equina nerve roots were seen on lumbar spine magnetic resonance imaging . Also noted was a diffuselyabnormalT2hypointensityof all visualized osseous structures, suggestive of a marrow-replacing process. A cauda equina nerve root biopsy specimen showed increased segmental demyelination  with macrophages scattered throughout the endoneurium. A bone marrow aspirate and biopsy specimen showed extensive involvement by lymphoplasmacytic lymphoma. Immunoelectrophoresis showed a small monoclonal IgM. He was prescribed intravenousimmunoglobulin(IVIG) (0.4 g/kg) twice a week for 8 weeks and once a week for an additional 8 weeks. He showed transient improvement with IVIG administration. His symptoms became significantly worse once he had stopped takingIVIGforafewweeks.Hewas also prescribed rituximab, 375 mg/m 2 intravenouslyonceaweekfor 4 weeks, for his lymphoma. The IVIG therapy was restarted, but throughout 6 months the benefit from this therapy progressively decreased. Chronic inflammatory neuropa

title: Primary intramedullary spinal cord lymphoma
abstract: Among the rare causes of myelopathies is primary intramedullary spinal cord lymphoma (PISCL). As PISCL is often underrecognized, delaying appropriate treatment, we sought to describe its presentation, imaging characteristics, and outcomes.  Mayo Clinic medical records, lymphoma database, and autopsies from 1996 to 2009 were searched. Inclusion criteria were clinical myelopathic presentation, intramedullary spinal cord abnormalities, and pathologically confirmed CNS lymphoma. Exclusion criteria were extramedullary lymphoma, secondary intramedullary lymphoma, or other myelopathic etiology. Clinical features, diagnostic methods, neuroimaging, treatment, and outcomes were assessed.  The 14 patients' median age at presentation was 62.5 years (range 41–82 years) and 10 were men (71%). Two had lymphoma risk factors (HIV infection 1; chronic immunosuppression postorgan transplant 1). Most had initial presumptive diagnoses of CNS demyelinating disease and definitive diagnosis of lymphoma was delayed a median of 8 months (range 1–22 months). CNS lymphoma was pathologically confirmed by biopsy (brain 6; spinal cord 4), CSF cytology (3), and autopsy (1). Most patients had multifocal, persistently enhancing lesions on spinal MRI and 8 had involvement of conus medullaris, cauda equina, or both. IV methotrexate was the initial treatment in 9 of 12 (75%) but lymphoma recurred in the majority. Half of the patients were wheelchair-dependent at 10 months and 2-year survival was 36%.  PISCL mimics other causes of myelopathy. Spinal MRI demonstrating multifocal lesions, persistent gadolinium enhancement, and conus medullaris or cauda equina involvement is characteristic. Pathologic confirmation often requires CNS biopsy. Despite chemotherapy, morbidity and mortality is high. Neurology® 2011;77:784–791

title: Magnetic Resonance Imaging of Primary Spinal Intramedullary Lymphoma
abstract: The authors report 2 cases of primary spinal intramedullary lymphoma and review all previously reported magnetic resonance imaging findings on this disease. The most common finding was a solid and homogeneously enhanced mass that was hyperintense on T2‐weighted images, without associated syringomyelia. In a few cases, swelling of the spinal cord was minimal.