Primary Kaposi sarcoma of the subcutaneous tissue

BACKGROUND: Involvement of the subcutis by Kaposi sarcoma (KS) occurs primarily when cutaneous KS lesions evolve into deep penetrating nodular tumors. Primary KS of the subcutaneous tissue is an exceptional manifestation of this low-grade vascular neoplasm. CASE PRESENTATION: We present a unique case of acquired immune deficiency syndrome (AIDS)-associated KS manifesting primarily in the subcutaneous tissue of the anterior thigh in a 43-year-old male, which occurred without overlying visible skin changes or concomitant KS disease elsewhere. Radiological imaging and tissue biopsy confirmed the diagnosis of KS. CONCLUSION: This is the first documented case of primary subcutaneous KS occurring in the setting of AIDS. The differential diagnosis of an isolated subcutaneous lesion in an human immunodeficiency virus (HIV)-infected individual is broad, and requires both imaging and a histopathological diagnosis to guide appropriate therapy.