The patient had a biopsy of the right temporal lobe and cerebellum. 


Sections show pieces of cerebellar tissue and cerebellar white matter. These structures show variable lymphoid infiltrates that are both superficial as well as perivascular and also intraparenchymal. The infiltrates are most prominent within block B. The individual cytologic characteristics range from mild to more pronounced nuclear pleomorphism. Some scattered mitotic figures are seen. T-cell infiltrates are highlighted by the CD3 immunoperoxidase study. The B-cell infiltrates are predominant and are highlighted by the CD20 immunoperoxidase study. There is no diagnostic evidence of demyelination in the LFB, LFB/Bielschowsky and Bielschowsky-stained sections.

Final Diagnosis: diffuse large B-cell CNS lymphoma.