Primary Effusion Lymphoma with Extracavitary Presentation and A T-Cell Immunophenotype: A Potential Diagnostic Pitfall

Abstract

<p class=MsoListParagraph style=margin:0in;margin-bottom:.0001pt;mso-add-space: auto;text-align:justify;text-indent:0in;line-height:normal;mso-list:l0 level1 lfo1; mso-mirror-indents:yes> 1. Abstract <p class=MsoNormalCxSpMiddle style=margin-bottom:0in;margin-bottom:.0001pt; mso-add-space:auto;text-align:justify;line-height:normal;mso-mirror-indents: yes> 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. <p class=MsoListParagraph style=margin:0in;margin-bottom:.0001pt;mso-add-space: auto;text-align:justify;text-indent:0in;line-height:normal;mso-list:l0 level1 lfo1; mso-mirror-indents:yes> 2. Keywords: <span style=font-size:10.0pt;font-family: times= new= roman,serif;color:black;mso-themecolor:text1=> Body Cavity Lymphoma; Effusion Lymphoma; Extracavitary Primary Effusion Lymphoma; KSHV/HHV8; PEL; Primary Effusion Lymphoma; T-Cell Primary Effusion Lymphoma