Methods (Diagnosis, investigations and treatment)
Diagnosis and investigation: Cerebral Magnetic resonance imaging (MRI) revealed a left fronto-parietal extra-axial lesion isointense on T1 weighted images with mass effect and a narrow perilesional edema on FLAIR images. This process measured 9×6.5×4 cm and was intensively enhanced on post gadolinium T1 weighted images with a typical ‘’dural tail sign” mimicking a convexity meningioma. Moreover, the mandibular tumefaction was identified as a voluminous lymph node. Intra operative findings showed an aggressive tumor with a poor plane of cleavage from the adjacent brain parenchyma. A total resection was achieved and the patient developed a postoperative aphasia and a right hemiparesis, which progressively resolved nearly completely (figure 1). Surprisingly, the first pathological examination revealed a normal lymph node parenchyma and we failed to find such case in previous literature reports. However, additional serological examination revealed an Ig M monoclonal gammopathy (rate of Ig M=29.2g/l) with Lamda light chain rate of 4.12g/l. Erythrocyte sedimentation rate was elevated to 50mm within the first hours. Moreover, Bence-Jones protein in urine was positive with also Lamda light chain monoclonal gammopathy. Protein electrophoresis in the cerebro spinal fluid (CSF) was normal albeit lymphoplamatic cells greater than 5/mm3 were found. Pathological reexamination of new serial slices of the surgical specimen revealed a lymph node parenchyma which architecture is completely dislocated by a tumoral proliferation consisting of an infiltration of small cells (lymphocytes) with some areas of plasmacytic differentiation associated to few immunoblasts. Some residual germinal center was noticed. Immunohistochemically, the vast majority of the cell population shows a diffuse expression for CD20 and CD79a without expression for CD5, CD10 and CD23. Ki 67 proliferation index was 5%. Therefore, the histopathological and immunohistochemical examination led to the final diagnosis of lympho-plasmacytic lymphoma. A complementary bone marrow biopsy demonstrated a lymphoplasmacytic infiltrate with a similar immunohistochemical profile (figure 2). These pathological and biological examinations were consistent with a fronto parietal Bing-Neel tumor complicating a WM.
Treatment: The patient was sent to the department of Clinical hematology to follow an adjuvant chemotherapy.