Extracavity primary effusion lymphoma presenting in a lymph node without lymphomatous effusions

Primary effusion lymphoma (PEL) is a distinct clinicopathologic entity associated with human herpesvirus 8 (HHV8), which usually presents as a lymphomatous body cavity effusion. Rare cases of PEL are extracavitary and manifest as a solid tumor mass. Here we report an unusual case of extracavitary PEL (EPEL) involving lymph nodes with no evidence of a body cavity effusion. The neoplasm was comprised of large pleomorphic cells with prominent nucleoli and frequent mitotic figures that expressed HHV8, EBV, CD38 and CD30, but lacked all lineage-specific markers. The patient was found to be HIV positive after the diagnosis of EPEL. Antiretroviral therapy initially reduces tumor size, but the patient expired three months later due to multiple complications. PEL and EPEL are differing manifestations of a rare disease entity as defined by the World Health Organization 2008 classification. It is unknown why a small subset of these cases forms extracavitary masses with or without malignant effusions. Comparison with mouse xenograft models may provide unique insights into the pathogenesis of this disease for possible future studies.