Plasmablastic lymphoma involving the penis: a previously unreported location of a case with aberrant CD3 expression.

Lymphomas of the penis are rare and can either arise at this site or be a manifestation of systemic disease. We report the case of an elderly man with a plasmablastic lymphoma (PBL) involving the uncircumcised penile prepuce. The neoplasm was composed of plasmablasts positive for monotypic immunoglobulin lambda light chain, CD3, CD79a, CD138 and Epstein-Barr virus encoded RNA (EBER), and was negative for CD2, CD5, CD7, CD20, and PAX5. This case is highly unusual for at least two reasons. The penile foreskin is a rare location for lymphoma and PBL at this site has not been reported. Secondly, the tumour was shown by immunohistochemistry to be positive for the T-cell marker CD3. Lineage ambiguity in terminally differentiated B-cell lymphomas has been reported to be closely related with immune compromise and is associated with Epstein-Barr virus infection. The literature on penile lymphomas is also reviewed.