Case Presentation: 41 y.o male with no past medical history presented with shortness of breath at rest. On presentation, he was febrile, tachycardic to 130’s/min and tachypneic to 32 breaths/min and saturating at 99% on room air. On auscultation, he had absent left-sided breath sounds. Chest X-ray demonstrated opacification of left hemithorax and CT chest revealed left pleural effusion with severe compressive atelectasis of the left lung with marked nodular thickening of the pleura. A transthoracic echocardiogram showed moderate pericardial effusion with no hemodynamic compromise.Hematological tests showed bicytopenia with anemia and thrombocytopenia that prompted an HIV test that was positive (CD4=186 cells/uL). Hepatitis B serology was also positive for active h hepatitis B infection. Thoracentesis was performed and 1.5L of serosanguinous fluid was removed and the pleural fluid cytology showed poorly differentiated cells. Cytopathology showed highly atypical, large, single malignant cells with irregular nuclear membranes, open to marginated nuclear chromatin, prominent nucleoli. Flow cytometry was negative and immunohistochemistry was positive for latent nuclear antigen-1 (LANA), CD30, and multiple myeloma 1 (mum1), paired box-5 (PAX5), human herpesvirus type 8 (HHV8) findings consistent with primary effusion lymphoma (PEL). He was started on cefepime and azithromycin along with a chest tube was placement for pleural fluid removal. He was started on chemotherapy with etoposide phosphate, prednisone, vincristine sulfate, cyclophosphamide, and doxorubicin hydrochloride (EPOCH) for PEL. He was also started on bictegravir, emtricitabine & tenofovir for HIV.

Discussion: Primary effusion lymphoma is a rare large cell non-hodgkin lymphoma localized predominantly in body cavities and less frequently in extracavitary regions. It is characterized by pleural, peritoneal, and pericardial lymphomatous effusions without solid tumor masses. HIV/AIDS and coinfection with HHV-8 in an immunocompromised host is the most common presentation. It is characterized by atypical lymphoid cells of B-cell origin, with large nuclei and prominent nucleoli. Diagnosis requires a positive HHV-8 as it is implicated in the pathogenesis of PEL. The virus encodes various genes involved in inducing cell proliferation and inhibiting apoptosis. At present, there are no standard guidelines for PEL management. Standard chemotherapy regimens for example EPOCH can be used, but the prognosis remains extremely poor. Treatment of HIV with highly active antiretroviral therapy is also recommended to be started as soon as possible on diagnosis of PEL.

Conclusions: PEL is a rare and aggressive B-cell neoplasm seen commonly in young to middle-aged men and is strongly associated with HHV-8 infection. It presents as malignant serous effusion without a solid tumor mass. It is reasonable for physicians to include PEL as one of the differentials in HIV patients with serous effusion. Testing for HIV and initiation of prompt treatment can help improve the chance of survival and the quality of life in such individuals.