Primary penile Kaposi sarcoma of the glans penis, nodular (Tumor stage) Presenting with an Isolated Grayish Exophytic Nodular Lesion on the Penis

Summary: To present a case of primary penile Kaposi sarcoma in an HIV-negative patient and discuss its clinical and histopathological features. A 70-year-old HIV-negative man presented with a 1.8 cm penile mass on the dorsum of the glans penis for five months. Clinical examination revealed a dorsal exophytic lesion on the midline glans penis, darker than the adjacent skin. Microscopic examination showed a nodular tumor composed of spindle cells arranged in fascicles with slit-like spaces containing red blood cells. Tumor cells showed mild nuclear atypia, mitotic activity, and hyaline globules. Lymphocytic infiltrates and hemosiderin deposition were identified. The peripheral margin of the tumor showed dilated capillaries with vascular channels. However, the surgical margin was free of tumor. Immunohistochemical staining showed positive CD31, CD34, and HHV8 staining but negative staining for panCK, SMA, and S100. The patient was diagnosed with primary penile Kaposi sarcoma, nodular stage. Primary penile KS is a rare but important differential diagnosis for penile masses, even in HIV-negative individuals. Other differentials include cutaneous angiosarcoma, hobnail hemangioma, spindle cell hemangioma, and kaposiform hemangioendothelioma. Early diagnosis and appropriate management are crucial for optimal patient outcomes.