Human immunodeficiency virus negative, immunocompetent primary effusion lymphoma with a complete response on R-miniCHOP

Primary effusion lymphoma (PEL) is a rare kind of extranodal non-Hodgkin large B-cell lymphoma that develops in the liquid phase in serous membrane-lined body cavities (perineum, pericardium, and pleura) without tumor masses. Kaposi sarcoma-associated human herpesvirus 8 (HHV8) is essential in establishing a diagnosis of PEL. An 84-year-old male with a past medical history of testicular cancer in his 40s presented with a chief complaint of shortness of breath which was attributed to a left pleural effusion. The flow cytometry indicated 32% small T lymphocytes (cluster of differentiation [CD]4: CD8 = 4.0:1), 9.0% small B lymphocytes without surface light chain expression, and 16% unknown phenotypic large cells. The cell block demonstrated large atypical lymphocytes with irregular nuclear membranes and coarse chromatin. The cells exhibited prominent nucleoli and relatively basophilic, abundant amphophilic cytoplasm. Multinucleated and Reed-Sternberg-like cells were also seen. We performed a panel of immunomarkers including HHV8 and ALK1. The tumor cells were positive for CD45, CD20, and HHV8 and negative for all other markers. Based on morphologic and immunophenotypical features, a diagnosis of PEL is rendered. Positron emission tomography/computed tomography showed an absence of fluorodeoxyglucose uptake in the lymph nodes and the spleen. Given his age, the patient started on treatment with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone at reduced doses (R-miniCHOP) and had a complete response. To our knowledge, there are no other reported cases of complete remission following an attenuated R-miniCHOP protocol in this clinical scenario.