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.