Primary effusion lymphoma with aberrant T-cell phenotype in an iatrogenically immunosuppressed renal transplant male: cytologic diagnosis in peritoneal fluid.

Primary effusion lymphoma (PEL) is an unusual class of non-Hodgkin's lymphoma that develops in body cavities, without associated mass lesions. It has been linked to human herpes virus 8 (HHV-8), an etiological factor of Kaposi's sarcoma. Although PEL is a B-cell lymphoma, the neoplastic cells are usually of the "null" phenotype by immunocytochemistry. The relative infrequency of this entity, the absence of wide casuistic allowing a better characterization, and its unfavorable outcome, strongly support the need of a deeper knowledge. We report the clinico-biological findings of a 49-year-old male who was iatrogenically suppressed patient for 29 years because of renal transplantation. This case was diagnosed cytologically as peritoneal PEL and confirmed histologically on peritoneal biopsies. The immune status for both HHV-8 and Epstein-Barr virus (EBV) was evaluated and showed positive immunostaining only for the former. The combination of the immunocytochemistry results with the existence of a clonal rearrangement in the immunoglobulin heavy chain gene (identified by PCR) was compatible with the diagnosis of PEL. The presence of T-cell markers was consistent with the diagnosis of PEL with an aberrant T-cell phenotype.