An unusual patient with shortness of breath—Clinical, radiologic, and pathologic pitfalls
Authors: Agata M. Bogusz, Robin Joyce, Gerald Kolodny, Thomas Buck, German Pihan, Parul Bhargava
Journal: American Journal of Hematology (2014)

A 44-year-old woman with asthma and 27-pack year smoking history presents to an outside institution with fever, progressive shortness of breath, and a 40 lb weight loss. Imaging studies show extensive mediastinal lymphadenopathy and bilateral pulmonary nodules with occasional central cavitations (Fig. 1). Dyspnea has a wide clinical differential commonly including asthma, chronic obstructive pulmonary disease, interstitial lung diseases, cardiomyopathy, and deconditioning 1. Diagnostic evaluation often involves laboratory studies (hematocrit, renal function, glucose, electrolytes, and thyroid function), pulmonary function tests, and imaging studies. In smokers, lung infiltrates and adenopathy are a concern for carcinoma, either primary lung or metastatic. Sarcoidosis, although associated with mediastinal adenopathy, typically lacks the lung findings noted. Bilateral pulmonary infiltrates with central cavitations in a smoker raises the concern for Langerhans cell histiocytosis (LCH); however, characteristically mid- to upper- zone reticulonodular opacities, stellate nodules, upper zone cysts, and sparing of costo-phrenic angles is seen. Mediastinal and/or hilar adenopathy are extremely rare in LCH. A lymphoma involving mediastinal nodes with lung compression and pneumonia is also a possibility. While her acute presentation of fevers and lung infiltrates may represent a superimposed infection, the significant adenopathy and weight loss make malignancy most likely. A right lower lobe transbronchial biopsy demonstrates scant bronchial tissue with a marked submucosal histiocytic infiltrate (Fig. 2). Rare cells with grooved nuclei morphologically suggestive of Langerhans cells were seen. No definite CD1a immunoreactivity was seen in scant tissue remaining on deeper sections. Histiocytes express HLA-DR and S100 (dim subset). Overall, the pathologic findings were felt to be suggestive of LCH. The patient was advised smoking cessation and started on steroid therapy (prednisone, 40 mg per day). LCH is a poorly understood histiocytic disorder of unknown etiology and highly variable biological behavior. Clinical presentation ranges from isolated lesions to multiorgan involvement 2. Pathologic findings include Langerhans cells (LC) with abundant eosinophilic cytoplasm and characteristically grooved nuclei, admixed with eosinophils and macrophages. LC are typically CD1a 3, S100, and Langerin (CD207) immunoreactive with Birbeck granules seen on electron microscopy. Unlike systemic LCH, pulmonary LCH is strongly associated with tobacco smoking. Symptoms did not improve and the patient was readmitted six months later for new cytopenias (WBC 11.6 K/µl, hemoglobin 7.7 g/dl, platelets 111 K/µl; with 95% neutrophils, 3% bands, 0% lymphocytes, and 2% monocytes). A marrow biopsy was hypercellular, mildly erythroid predominant with an interstitial infiltrate of histiocytes including some with hemophagocytosis (Fig. 3). No LC were seen on light microscopy or by CD1a immunostaining. A diagnosis of macrophage activation syndrome was rendered since the patient did not meet clinical and laboratory criteria for hemophagocytic lymphohistiocytosis (HLH). The marrow findings suggest macrophage activation syndrome and/or evolving HLH. HLH is characterized by a fever, hepatosplenomegaly, cytopenias, hyperferritinemia, hypertriglyceridemia, and hypofibrinogenemia. Primary HLH results from genetic defects of natural killer cells and cytotoxic T-cells, while secondary HLH is associated with infections or malignancies, both non-hematologic and hematologic. Lymphoma-associated hemophagocytic syndrome (LAHS) is a rare entity almost always associated with fever and splenomegaly 4. The prognosis is better in B-cell malignancy associated LAHS than with T/NK-cell lymphomas 5. In this patient with mediastinal adenopathy, weight loss, and marrow findings of macrophage activation, our index of suspicion of an underlying malignancy is high. The patient continued to receive prednisone but had fevers, night sweats, progressive fatigue, and dyspnoea requiring readmission a month later. Cervical lymphadenopathy and worsening cytopenias were noted (WBC 10.9 K/µl, hematocrit 18%, platelets 90 K/µl). She received increasing steroids (methylprednisolone/Solu-Medrol®250 4x/day), numerous transfusions (12 red cell and 7 platelet transfusions over 2 weeks), and levofloxacin for possible pneumonia, with no improvement and was transferred to our institution. She remained febrile but infectious workup returned negative. Imaging showed extensive right lung consolidation with numerous nodules, hilar, supraclavicular, axillary, retroperitoneal lymphadenopathy, and hepatosplenomegaly. A bone scan showed increased activity bilaterally in proximal and distal femuri, tibia, sternum, and periorbital anterior skull area. No definite lytic or sclerotic lesions were seen on skeletal survey. At transfer, the patient had two tissue biopsies; a transbronchial biopsy with histiocytic infiltrates suggestive of LCH and a marrow biopsy with an extensive histiocytic infiltrate; thus the entire spectrum of histiocytic malignancies was under diagnostic consideration. The Histiocyte Society classifies histiocytic disorders into Group I (LCH), Group II (non-LCH, mononuclear phagocyte histiocytic proliferations such as Erdheim–Chester disease (ECD) and Rosai–Dorfman disease), and Group III, which consists of malignant histiocytic disorders 6, 7. The bone scan findings of increased activity of long-bones bilaterally and possible maxillary involvement raised the concern for ECD which is a rare, non-LCH histiocytic disorder of unknown etiology with an onset in middle-age 8, 9. Characteristically, bilateral involvement of long bones is seen with diaphyseal and metaphyseal sclerosis; axial skeleton and flat bones are only rarely involved. Histologically, bony infiltration by lipid-laden CD68-immunoreactive foamy histiocytes and multinucleated Touton giant cells are seen. More than 50% patients exhibit extra-skeletal manifestations including lung, liver, spleen infiltration, and endocrine disruptions like diabetes insipidus 8. Unlike LCH, ECD histiocytes are unreactive for S-100 or CD1a and lack Birbeck granules. Other differential diagnostic considerations included an aggressive systemic histiocytic sarcoma, pending additional tissue analysis. Rosai–Dorfman disease was also being considered given this patient's adenopathy; the latter classically affects head and neck region although various extranodal sites including bones can be affected. Rarely, this can be seen in association with other malignancies including lymphomas 10-12 and solid tumors 13. A careful re-review of prior biopsies and a nodal biopsy is recommended. All outside pathology biopsies were requested for re-review. The transbronchial biopsy had a non-specific histiocytic infiltrate without significant cellular atypia or eosinophils. While the number of eosinophils in pulmonary LCH can be highly variable, no clear CD1a was demonstrable which, together with the radiologic findings, argued against a diagnosis of LCH. The marrow had increased interstitial macrophages, including some with hemophagocytosis. Lack of emperipolesis and S100 argued against Rosai–Dorfman disease, while absent CD1a was against LCH. The histiocytes lacked cytologic atypia of histiocytic sarcoma. No other atypical infiltrates were seen on careful review of multiple sections. Overall, the findings were felt to be that of macrophage activation or possibly hemophagocytic syndrome, likely secondary to a malignancy present elsewhere, and a re-biopsy was advised. An excised cervical node showed a diffuse infiltrate of highly atypical medium-sized mononuclear cells (Fig. 4A–C), admixed large multinucleated cells with hyperchromatic nuclei (Fig. 4C), and binucleate Hodgkin/Reed–Sternberg (HRS)-like cells (Fig. 4D). Mummified cells, atypical mitotic figures, and necrotic areas containing neutrophilic infiltrates were present (Fig. 4A), but background inflammatory infiltrate was scant. Negative HMB-45, S100, CD1a, and pancytokeratin stains made melanoma, LCH, and carcinoma unlikely. The atypical cells were variably immunoreactive for CD45, lacked pan-B markers (CD20, CD79a), however, expressed PAX5 (weak intensity; Fig. 5C), CD30 (in 20–30% of total cells; Fig. 5A), fascin, and occasionally CD15 (Fig. 5B; Supporting Information Table SI). They had a post-germinal center profile (MUM1+, BCL-6 subset+, CD10−), strong BCL-2 staining, absent B-cell transcription factors (Oct2, BOB1), and absent immunoglobulin light chains (kappa, lambda). Aberrant CD4, CD45RO, and CD25 was noted, but other T-cell markers (CD2, CD3, CD5, CD7, CD8, CD43, TIA-1), ALK-1, clusterin, EMA, and CD56 were absent. Many had nuclear C-REL immunoreactivity (Fig. 5D). Latent membrane protein and in situ hybridization studies for Epstein Barr virus-encoded RNA were negative. While large cells had membranous CD163 and CD68 immunoreactivity, and to a lesser degree FXIII, while lysozyme staining was restricted to interspersed small- to medium-sized histiocytes (Fig. 6). Flow cytometry was non-contributory. Two clonal peaks were noted on B-cell gene rearrangement studies using polymerase chain reaction (PCR) for IgH gene (Supporting Information Fig. S1) while T-cell receptor (TCR) was polyclonal by TCR-γ gene rearrangement (not shown), verified by repeat testing. Overall, the findings were of a malignant lymphoma of B-cell phenotype. Differential diagnoses included a treatment-altered (given several months of steroid treatment preceding this biopsy) classical Hodgkin lymphoma (cHL) or, alternatively, an unclassifiable lymphoma with features intermediate between cHL and large B-cell lymphoma (“gray zone” lymphoma) which was favored. The lymph node was replaced by a highly atypical malignant infiltrate. On initial immunoprofiling, B- or T-cell markers were absent. However, immunoreactivity for histiocytic markers (CD4, CD163, Factor XIII, fascin) was noted. ECD remained a tantalizing differential diagnostic consideration in this patient with bony and lung involvement, but characteristic Touton-type giant cells were absent and unlike ECD cells which are typically small, oval to occasionally spindled and bland, the cells were large and highly atypical. Fascin immunoreactivity described in ECD is non-specific, and has been shown in cHL and other lymphomas. Finally, CD30 and PAX5 expression are against a diagnosis of ECD. Although prominent CD163 and CD68 immunoreactivty, and to a lesser extent FXIII staining, raised concerns for a histiocytic sarcoma, the pattern of staining was membranous and not cytoplasmic 14. Since lysozyme staining was restricted to smaller histiocytes interspersed between larger malignant cells, the membranous CD163 immunoreactivity was felt to represent histiocytic cytoplasmic processes encircling tumor cells. Notably, cHL may have abundant CD163 immunoreactive histiocytes 15. The case again highlights pathologic diagnostic pitfalls. Pathologists need to be cognizant of non-lineage markers that may be aberrantly expressed in various tumor types, be familiar with sub-cellular localization of immunoreactivity and, when necessary, evaluate a panel of markers to resolve discrepancies. Another CD30-immunoreactive lymphoma lacking significant inflammatory background is a T/null cell anaplastic lymphoma 16. Our case highlights the utility of PAX5 in establishing a B-cell lineage 17 in cases lacking standard T and B markers. Although rare PAX5-positive T cell lymphomas have been reported 18, the subsequent molecular studies confirm a B-cell origin in our case. Notably, aberrant T-cell markers (including CD4) have been reported in cHL 19, 20 as well as non-Hodgkin lymphomas (NHL) 21 and rare cHL cases harboring TCR rearrangements have been reported 22. Amongst B-lineage lymphomas, key morphologic hallmarks of Hodgkin lymphoma vis-à-vis NHL include (a) Hodgkin and Reed–Sternberg cells (HRS), classically with T-cell rosetting and (b) an abundant background non-neoplastic cells. While large HRS-like cells were noted with a characteristic cHL immunophenotype, in contrast to cHL, malignant cells occurred in sheets, and an inflammatory background was scant. Nonetheless, our case represents a diagnostic dilemma as months of steroid treatment prior to tissue sampling could potentially reduce the inflammatory background characteristic of cHL, and presents a pitfall that merits consideration. Presence of neutrophilic infiltrates within necrotic foci, and female sex of the patient also favor cHL over mediastinal gray zone lymphoma (MGZL) where a majority of patients are young men (20–40 years) 22. Although steroid altered cHL could not be entirely excluded, based on findings in the specimen at hand, in particular morphology favoring diffuse large B-cell lymphoma with an immunophenotype closer to CHL, a “B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and classical Hodgkin lymphoma” (World Health Organization (WHO) 2008 classification) was favored. MGZL denotes cases with transitional features between cHL and primary mediastinal large B-cell lymphoma (PMBL) 23, 24 and generally have a poorer outcome. A composite lymphoma of cHL and PMBL, a phenomenon that may be related to MGZLs also remained a consideration 9. C-Rel expression noted in our case is associated with NFκβ up-regulation and has been demonstrated in cHL, PMBL, as well as in MGZL 25. Growing evidence suggests that cHL and PMBL share common pathogenetic mechanisms including activation of the NFκβ pathway 26. They show similarities in morphology, immunophenotype, genomic aberrancies, and gene expression profiling and not surprisingly there is an overlap of these features in MGZL cases. Recent methylation profiling studies demonstrate clear distinction of MGZL from cHL as well as PMBL that justifies its assignment to a separate WHO category 27. Analysis of additional diagnostically difficult cases like the one presented here needs to be explored in the future to better understand the biology of these tumors. The treating physicians debated between traditional treatment for cHL with doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) versus NHL-type regimens such as cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP). Significant respiratory compromise precluded bleomycin use and she was felt to be steroid-resistant secondary to prolonged (>6 months) previous exposure. She received EPOCH (etoposide, doxorubicin, vincristine, prednisone, and cyclophosphamide) that has been widely used in treating cHL, NHL, PMBCL, and other aggressive lymphomas, with resolution of fevers, pulmonary symptoms, and improvement in blood counts and weight. However, a Positron emission tomography (PET) scan after six cycles showed interval progression. A cycle of ICE (ifosfomide, carboplatin, etoposide) resulted in a mixed response and she was enrolled in a Phase 2 study of the anti-CD30-directed chemo-immunoconjugate-brentuximab. Initial radiologic response was followed by progression after the 4th cycle and she was taken off-study. She then received five cycles of Gemcitabine, liposomal doxorubicin, and Navelbine, followed by two cycles of MINE (Mesna, Ifosfamide, Etoposide, Mitoxantrone), and then Bendamustine and Rituxan, all with continued disease progression. She received two cycles of IGEV (Ifosfamide, Gemcitabine, Vinorelbine) complicated by right lower lobe pneumonia. She developed hypotension, hyperbilirubinemia, renal failure, and metabolic encephalopathy and expired 22 months after initial diagnosis. The regimens represent all of the significant agents with activity against cHL. Each regimen was dose intense. The mixed response to each of these agents suggested significant tumor heterogeneity. The goal was to proceed to high dose therapy with autologous stem cell transplant, but she was never stable enough. The use of allogeneic transplant was considered, but a suitable donor was not found and the patient's clinical condition rapidly deteriorated. This is a challenging case with a complex clinical, radiologic, and pathologic presentation and highlights several diagnostic pitfalls associated with tissue sampling, tumor associated macrophage activation syndromes, as well as alteration of pathologic findings due to prolonged steroid use. The case highlights the importance of a multi-disciplinary approach in evaluating a patient. Even though the biopsy demonstrated a possible collection of LC, attention to the impressive imaging findings that are not characteristic of LCH, presence of adenopathy, and a 40 lb weight loss over the past year, should have raised suspicion that there may be an underlying malignancy. Expansion of LC can be seen in otherwise healthy smokers as well as in association with other pulmonary disorders such as pulmonary fibrosis. Moreover, pulmonary LCH has been associated with several malignant and non-malignant tumors. The pathologic findings of the small transbronchial biopsy did not explain the clinical presentation. Sampling is an important caveat in all pathologic diagnoses, which pathologists and clinicians alike need to be cognizant of. A large number of diagnostic problems may arise in pulmonary pathology on small biopsies that can be related to biopsy artifacts, non-specific changes, benign reactive processes that mimic neoplastic disorders, and finally malignant tumors mimicking benign disorders. In addition, a neoplastic process may be missed if an appropriate area is not sampled which could have been possible in this case given the significant lung consolidation on the CT scan. Where appropriate, a re-biopsy of a different site or a larger excisional biopsy should be considered. Another confounder in this unusual presentation was the exuberant histiocytic response, which besides being noted in the marrow biopsy, led to an unusual bone scan mimicking ECD. Furthermore, the immunohistochemical expression pattern (notably fascin, CD4 in atypical cells, and upon initial review, FXIII and CD163 immunoreactivity) was confusing. However, all cHL tested are known to express fascin, and aberrant T-cell markers are often expressed in RS cells. FXIII is not well studied in cHL with only a rare study describing FXIII immunoreactivity in tumor infiltrating macrophages of cHL; upon review of other macrophage markers (especially lysozyme), FXIII was felt to be staining processes of interspersed macrophages. This unusual case highlights the overlap in radiologic, pathologic, and even immunohistochemical findings between neoplastic histiocytic disorders such as ECD versus exuberant reactive histiocytic proliferations associated with malignancies. Steroid therapy can significantly alter histopathologic features, particularly in lymphoid malignancies. In NHL, the malignant population can be temporarily significantly diminished, leading to non-diagnostic biopsies. In Hodgkin lymphomas, the characteristic and diagnostically useful background reactive milieu may be significantly reduced, leading to difficulties in accurate sub-classification. Additional Supporting Information may be found in the online version of this article. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.