BACKGROUND Human herpesvirus-8 (HHV-8)-associated diffuse large B-cell lymphoma, not otherwise specified (DLBCL, NOS), is a rare form of lymphoid malignancy. It poses unique challenges in diagnosis in the setting of human immunodeficiency virus (HIV) infection and concomitant multiorgan dysfunction. CASE REPORT We describe the case of a 26-year-old man who initially presented with pre-syncope and was found to have HIV, with a CD-4 count of 20 cells/μL. His initial clinical presentation was significant for nonspecific symptoms, isolated anemia, and bilateral pleural effusions without gross lymphadenopathy, which was initially attributed to acute HIV infection. However, his hospital course was complicated by anasarca, renal failure, liver dysfunction, pancytopenia, and microscopic hematuria, which required a more comprehensive diagnostic evaluation. Progressive pancytopenia prompted a bone marrow biopsy, which ultimately revealed HHV-8-associated DLBCL, NOS (HDN). We describe his complicated hospital course and eventual diagnosis of HDN. This patient’s broad differential diagnoses and overlap among various clinical syndromes posed a significant diagnostic challenge. Additionally, his multiorgan failure limited his treatment options. CONCLUSIONS The management of HHV-8-associated DLBCL, NOS is complex, requiring a multifaceted approach to ensure prompt diagnosis and treatment, especially given difficulty in arriving at an accurate diagnosis due to the significant overlap with other lymphoproliferative disorders and lack of standardized treatment. We highlight the challenges and paucity of data available for management of HDN in the context of a diagnostically challenging case. We discuss the current limitations in diagnosis and treatment of this rare malignancy and the necessity of further investigation, especially in medically complex patients.