Typical epidemiology and imaging features of PCNSL. 

Macroscopic: A. B. C. Labeled "Corpus callosal lesion"

Microscopic: A. B. C. The tissue is cellular, showing infiltration by large atypical lymphoid cells with frequent apoptosis. Cell nuclei show weak pleomorphism and small nucleoli and atypical mitoses. Cells are immunoreactive with CD20, BcL2 (100% cells), BcL6 (60% cells), Ki67 in 100%. Cells are negative for CD3, CD 30, and EBV.

Diagnostic opinion:  A. B. C. Corpus callosal lesion – high-grade B cell lymphoma.