The patient went on to have a biopsy. 

Histology

MICROSCOPIC DESCRIPTION:

Sections of brain tissue show a diffuse infiltrate of atypical lymphoid cells. Tumor cells demonstrate enlarged oval pleomorphic nuclei with vesicular chromatin and prominent nucleoli. Frequent mitoses and apoptoses are present. The tumor demonstrates a perivascular distribution. Immunohistochemically tumor cells stain CD20+, CD10-, BCL2+, BCL6+, MUM1+, CMYC+ (50%), EBER-CISH- and CD3-.

FINAL DIAGNOSIS: Diffuse large B-cell primary CNS lymphoma.