Case Report: The deceptive vein - when benign-appearing laryngeal lesions mask primary laryngeal classic Kaposi sarcoma.

Introduction: Primary laryngeal Kaposi sarcoma (KS) is exceptionally rare in HIV-negative, with only 20 reported cases. The diagnosis is challenging as it may histologically mimic benign vascular lesions in early-stage KS, which leads to delayed diagnosis. We present a case of a classic KS with primary laryngeal involvement in an HIV-negative male. highlighting the diagnostic pitfalls and the critical role of HHV-8 immunohistochemistry. Case presentation: A male patient in his sixties with a 40-pack-year smoking history presented with progressive hoarseness and nasal obstruction. Six years earlier, he had been diagnosed with a laryngeal lymphangioma, and a subsequent supraglottic lesion six years later was diagnosed as hemangioma, both with excisional biopsy. Several months later he developed dysphagia and diffuse cervical, axillary, and mediastinal lymphadenopathy. MRI revealed a 5.7 cm ill-defined left supraglottic mass with heterogeneous enhancement and necrosis. Biopsy of the laryngeal lesion and a cervical lymph node demonstrated spindle cell proliferation with positive staining for CD31, CD34, D2-40, and HHV-8, confirming the diagnosis of Kaposi sarcoma. HIV testing was negative. Subsequent examination revealed new violaceous nodular lesions on both lower extremities. He received local radiotherapy and systemic liposomal doxorubicin. Six months after treatment, he developed progressive dysphagia and hoarseness due to radiation-induced fibrosis, not recurrence. His course was complicated by recurrent aspiration pneumonia, leading to septic shock and death. Conclusion: Primary laryngeal Kaposi sarcoma can occur in HIV-negative patients and may be misdiagnosed as benign vascular lesions such as lymphangioma or hemangioma. A high index of suspicion is warranted for any vascular spindle cell lesion of the larynx, regardless of HIV status. HHV-8 immunohistochemistry is an essential confirmatory tool that should be performed early, even when initial biopsies appear benign.