Kaposi's sarcoma-associated herpesvirus-positive primary effusion lymphoma arising in the subarachnoid space.

Primary effusion lymphoma (PEL) is a rare and distinctive type of B-cell non-Hodgkin's lymphoma (NHL) that occurs primarily, although not exclusively, in patients with AIDS. It usually develops as a lymphomatous effusion in the absence of a tumor mass, characteristically contains the Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 (KSHV/HHV-8), usually also contains the Epstein-Barr virus (EBV), displays a characteristic cytomorphology bridging immunoblastic and anaplastic large cell lymphoma, often expresses an indeterminate immunophenotype, and a B-cell genotype. Thus far, PEL has been limited almost entirely to the pleural, peritoneal, and pericardial cavities. We describe a NHL occurring in a gay man with AIDS that is typical of PEL in that it arose in a body cavity or space without an associated tumor mass, displays the cytomorphology typical of PEL, is a clonal B-cell neoplasm, and contains KSHV as well as EBV. This case is singularly distinctive in that it is the first case of PEL reported to arise in the subarachnoid space. This unique case further supports the strong association between KSHV and malignant lymphoma arising in body cavities and growing as an effusion.