Microscopic examination of the touch prep specimens reveals scattered non-cohesive lymphoid cells against a background of widespread necrosis. The viable lymphoid cells show significant anisocytosis and pleomorphism.
Microscopic examination of the permanent sections reveals occasional fragments of viable CNS tissue and multiple fragments of necrotic debris. Scattered throughout the necrotic areas are lymphoid cells, most of which are small and unremarkable. However, some are large and pleomorphic. Within some of the more viable fragments of the brain biopsy, aggregates of pleomorphic large lymphoid cells with a perivascular distribution are seen. Scattered mitoses are seen. Immunohistochemical staining for the leukocyte common antigen is positive for both the neoplastic and reactive lymphocytes. Immunohistochemical staining for B cell antigens is also positive for the larger perivascular lymphoid cells. Immunohistochemical staining for T cell markers is positive for many of the smaller cells but not the larger cells.
Viral inclusion are not seen, and immunohistochemical staining for cytomegalovirus antigens is negative. Insitu staining for Epstein Barr virus was positive in many of the large lymphoid cells. This case was reviewed by Steven Swerdlow, M.D. who agrees with the diagnosis and interpretation.