A80-4-42 Extracavitary Primary Effusion Lymphoma Presenting as Right-Sided Pleural Effusion in an Hiv-Positive Patient: A Rare Manifestation of a High-Grade Lymphoma

Abstract Primary Effusion Lymphoma (PEL) is a rare, high-grade non-Hodgkin lymphoma typically associated with HIV and HHV-8 co-infection. While classic PEL presents as lymphomatous effusions in body cavities without mass formation, extracavitary variants may involve solid organ or soft tissue masses without effusion. Primary Effusion Lymphoma is an uncommon and aggressive B-cell lymphoma associated with HHV-8 infection, primarily affecting immunocompromised individuals such as those with AIDS. The extracavitary variant is even rarer and often mimics other malignancies or infections. Early diagnosis is challenging due to nonspecific symptoms and imaging findings. Recognition of this entity is critical given its rapid progression and poor prognosis. This is the case of a 38-year-old male with PMHx of HIV, non-compliant with treatment who presents to the ER due to shortness of breath and hemoptysis. Patient reports that symptoms started about a few months ago yet hemoptysis started 4 days prior to ER presentation. Patient also with recent weight loss and poor appetite, as well as general malaise and weakness. Reports that every time he coughs it presents with streaks of blood of about a sputum full of bright red blood, denied fever, chills, sick contacts. Patient underwent diagnostic thoracentesis that yielded 1150 mL of serosanguinous fluid. Pleural fluid analysis showed an exudative effusion (Protein 4.8 g/dL, LDH> 2500 U/L) with hypercellular with numerous pleomorphic neoplastic cells with mixed nuclear features, including enlarged irregular nuclei, prominent nucleoli, increased abnormal mitotic figures, plasmacytoid cells and Reed-Stenberg-like cells as per microscopy description with positive CD30+, CD138+, IRF4 + (MUM1) by flow cytometry. Diagnosis of Extracavitary Primary Effusion Lymphoma presenting with a pleural-based mass and associated effusion was made. Primary effusion lymphoma remains a rare but aggressive AIDS related non-Hodgkin lymphoma that often poses a diagnostic challenge, especially in its extracavitary form. PEL accounts for almost 4% of all HIV-associated lymphomas and extracavitary variants constitute to approximately 20-30% of PEL cases. Risk factors include profound immunosuppression, high HIV viral loads, co-infection with HHV-8 which although it is universally present in PEL it was not the case with our patient and in some cases co-infection with Epstein-Barr virus. This case underscores the importance of considering extracavitary PEL in the differential diagnosis of pleural effusion in HIV-positive patients, especially those with poor ART adherence. Early pleural fluid analysis and aggressive multidisciplinary treatment are critical for management and prognosis. This abstract is funded by: none