When Unilateral Leg Swelling Is Not Deep Vein Thrombosis: A Case of Disseminated Kaposi Sarcoma Revealing Advanced Human Immunodeficiency Virus.

Kaposi sarcoma (KS) is an acquired immunodeficiency syndrome (AIDS)-defining malignancy that can involve the skin, lymph nodes, and visceral organs in patients with advanced human immunodeficiency virus (HIV). We report the case of a 35-year-old man with no known prior medical history who presented to the charity care clinic complaining of recurrent thrush and two weeks of progressive right lower extremity swelling. His physical examination revealed painful, pruritic violaceous papules and plaques over the proximal right thigh that had been present for one week. He was referred to the emergency department (ED) for further workup. Venous duplex ultrasonography was negative for deep venous thrombosis (DVT). He was found to have a newly diagnosed HIV-1 infection with advanced immunosuppression, oral thrush with odynophagia and dysphagia concerning for esophageal candidiasis, and a reactive rapid plasma reagin titer of 1:32 with retinal white dot lesions concerning for ocular syphilis. Computed tomography (CT) demonstrated diffuse right lower extremity soft tissue edema, extensive right inguinal, external iliac, and intrapelvic lymphadenopathy, bilateral axillary lymphadenopathy, and multiple bilateral pulmonary nodules. Punch biopsy of a right thigh lesion revealed KS with tumor cells positive for cluster of differentiation 31 (CD31), CD34, ERG, and human herpesvirus 8 (HHV-8), and an excisional lymph node biopsy demonstrated findings consistent with disseminated KS. Furthermore, cerebrospinal fluid (CSF) analysis confirmed neurosyphilis with a positive Venereal Disease Research Laboratory (VDRL). He was treated with bictegravir/emtricitabine/tenofovir alafenamide, trimethoprim-sulfamethoxazole prophylaxis, fluconazole, and intravenous penicillin G. The patient showed early clinical improvement with resolution of ocular symptoms and a declining HIV viral load following initiation of therapy and before discharge. This case highlights biopsy-proven KS as the presenting manifestation of previously undiagnosed advanced HIV, with unilateral limb lymphedema and pulmonary nodules suggesting disseminated disease. Additionally, our case underscores the need for early HIV testing in patients with recurrent mucocutaneous candidiasis and unexplained lymphedema, and for prompt evaluation of concomitant opportunistic and sexually transmitted infections.