A historical cerebral amyloidoma (SPA) classified retrospectively as AL𝛌-type. A case report

An unusual, walnut-sized tumor was removed from the left occipital lobe of a 46-yearold woman’s brain (SPA) who had suffered severe progressive cerebral symptoms for the last 4 years. Histologic examination of this tumor and a rectum biopsy revealed a local cerebral amyloidoma, which was cited in a publication in 1981 [1]. Recently, the respective paraffin block was retrieved, and amyloid was verified histologically and typed immunohistochemically using a set of validated commercial antibodies that have shown high precision and sensitivity in more than 660 cases examined in a blinded fashion [2]. The results on SPA revealed only ALl amyloid based on a consistent diagnostic immunohistochemical reaction, while the reactivities against nine other amyloid types were found to be inconsistent or excluded negative. This is in line with results on the vicinal monoclonal plasmocytes showing only l-reactivity. The data of this amyloidoma are therefore in part similar with those of other CNS amyloidomas as summarized elsewhere [1,3,5]. Introduction: Cerebral amyloidomas without systemic disease are very rare. This lesion has been reviewed [3,4]. Clinically, the amyloidomas can mimic various cerebral lesions, but they are progressive or intermittently progressive in all cases. First, symptoms can be headache, seizures and visual field defects, loss of hearing, and instability of gait, but also mental decline. The pattern of symptoms vary from patient to patient in relation to the site of the amyloidoma. In some patients, the diagnosis of atypical multiple sclerosis was made at the onset of the disease [5] Stereotactic biopsy has been used for its detection since 1995 [6]. In some cases, the amyloidoma has been surgically removed as in the historical case presented here [1]. The survival seems limited in most cases, but some patients survived more than 10 years even without surgery. This historical amyloidoma of Spaar et al. [1] is enumerated as the third case in the world literature [3,5], but it has never been classified stringently. Prof. Spaar later submitted a paraffin block of this very early published amyloidoma to our laboratory for classification of the amyloid. Material and methods: The patient: As summarized by Spaar et al. [1], a 46-year-old woman (SPA) was admitted after a 3.5-year-history of a progressive mental depression. In 1979, with an unsteady gait caused by a defective visual loss that occurred first in the right eye in 1976 and 10 days later in the left eye due to a paracentric scotoma from chorioretinitis of unknown etiology, this patient was treated with steroids and was reported to have disappeared without having detected the cause. All other examinations including laboratory tests and the ESR were within the normal range. On examination, various reflexes were abnormal, and she later complained of increasing visual disturbances, headaches, and recurrent periods of amnestic dysphagia. The results of the electroencephelogram showed local theta-waves and delta-waves and the arteriography showed some displacement of blood vessels in the left parietooccipital region. The computer-tomography showed a hypodense area that appeared enlarged a few months later. The tissue excisate and historic evaluation: In January 1980, a walnut sized, endured tumor was surgically removed from the left occipital lobe of the cortex and the subcortical white matter. The histological examination of this excisate yielded regular amyloid globes, irregular amyloid masses (see Figure 1) and non-occluding vascular amyloid with Congo red and thioflavin-T staining. The vicinity revealed lymphoid cells, plasmocytes, and some monocytes as well as multinucleated giant cells. Immunohistochemistry revealed only the presence of IgM and some l-reactivity in the central part of some of the acelluar amyloid deposits (not documented), but the amyloid was not regarded as typed [1], and a paraffin block was send to us for typing. Reexamination of the amyloidoma: From the retrieved paraffin block (Our code: Am 3495), sections of 4 mm were prepared, stained with Congo red, and the amyloid was evaluated in polarized and fluorescent light [6]. The classification was performed using a commercial set of antibodies (‘amYkit’; www.amymed.de) for typing of the various amyloids as summarized [6,8]. Results and discussion: The amyloid of the cerebral excisate was stained with Congo red as seen microscopically in bright light. In addition, it displayed the known orange-red fluorescence in blue excitation. In polarized light, it revealed the pathognomonic characteristic green birefringence. Immunohistochemical analysis was performed with three sets of antibodies, (a) the commercial antibody set (‘amY-kit’) in order to see whether the amyloid belonged to the 98% of more common amyloids 114