primary effusion lymphoma with extracavitary presentation and a t cell immunophenotype a potential diagnostic pitfall

1. Abstract

Primary Effusion Lymphoma (PEL) is a unique immunodeficiency-associated malignancy that requires infection with Kaposi sarcoma herpesvirus/human herpesvirus 8 (KSHV/HHV8). Although thought to arise from mature B-lymphocytes, PEL typically has a null Immunophenotype but can very rarely show lineage specific aberrancies, including aberrant T-cell markers. Here we present one such case of PEL where aberrant T-cell markers led to a misdiagnosis of peripheral T-cell lymphoma. We performed a review of the literature to identify similar cases of PEL with strong T-cell antigen expression. Most cases occurred in men who were HIV positive or otherwise immunodeficient. Many were EBV positive. Rare cases demonstrated T-cell receptor gene rearrangements. Postulated theories for the cause of disordered differentiation include immunodeficiency and/or EBV infection. The expression of T-cell antigens on PELs may be a source for error in diagnosis and awareness of this correlation is of practical diagnostic relevance.

2. Keywords: Body Cavity Lymphoma; Effusion Lymphoma; Extracavitary Primary Effusion Lymphoma; KSHV/HHV8; PEL; Primary Effusion Lymphoma; T-Cell Primary Effusion Lymphoma