This patient had had previously diagnosed lymphoma, and now had a cerebral recurrence. The patient went on to have a biopsy.

Histology

MICROSCOPIC DESCRIPTION: 

The sections show a densely cellular malignant tumor in the white matter. It forms diffuse sheets and cuffs around the blood vessels. The tumor cells are intermediate in size. They have enlarged clefted and hyperchromatic nuclei, prominent nucleoli and scanty cytoplasm.

The tumor cells are CD20, PAX-5, bcl-2, bcl-6 and MUM1 positive. The Ki-67 index is about 80%. They are CD3 and CD10 negative. There is insufficient tissue for EBER-CISH. The features are those of diffuse large B-cell lymphoma with activated B-cell-like phenotype.

FINAL DIAGNOSIS: 

Diffuse large B-cell CNS lymphoma.