Panniculitis-Like Presentation of Extracavitary Primary Effusion Lymphoma

Primary effusion lymphoma (PEL) is defined as a HHV-8-associated large B-cell lymphoma, which favors HIV-infected young adults, typically presenting as a serous (pleural, pericardial, or peritoneal) effusion with no identifiable tumor mass. Uncommon instances of lymphoid proliferations with the same morphology, immunophenotype, and molecular features as PEL, but occurring as a solid tumor mass without serous cavities involvement, have been termed extracavitary (or solid) variant of PEL. We hereby report the exceptional case of a HIV-associated extracavitary PEL primarily localized to the skin and exhibiting a panniculitis-like presentation. Primary cutaneous presentation of extracavitary PEL is exceedingly uncommon, with only 6 cases previously described in the literature. In light of its atypical immunophenotype, the differential diagnosis in case of skin involvement by extracavitary PEL is challenging: demonstration of HHV-8 infection in neoplastic cells is of pivotal importance. Our case is further atypical in that the lymphoid proliferation underwent complete and protracted regression solely by establishment of highly active antiretroviral therapy.