MICROSCOPIC DESCRIPTION: 1-4. Paraffin sections show fragments of brain parenchyma. All of these show varying degrees of infiltration by atypical large mononuclear cells distributed predominantly as single cells between fibre tracts. Large solid aggregates of atypical cells are seen in specimen 4. Infiltration through the walls of several small calibre blood vessels is also seen in specimen 4. There is florid reactive astrocytic gliosis in all specimens. No evidence of demyelination is seen.
Immunohistocheistry shows the atypical large cells to be CD20+, bcl-2+, bcl-6+, MUM1+, CD3-, CD10-, GFAP-, cytokeratin CAM5.2-, CD68-, EBV-. The features are of lymphomatosis cerebri (non Hodgkin's large B cell - non germinal centre phenotype)
DIAGNOSIS: 1-4: Brain biopsies: Lymphomatosis cerebri (non Hodgkin's large B cell - non germinal centre phenotype)
SUPPLEMENTARY REPORT: About 20% of the tumour cells are c-myc immunostain positive. About 25% of the cells are p53 positive.