A case report of a renal anastomosing hemangioma and a literature review: an unusual variant histologically mimicking angiosarcoma

Anastomosing hemangioma, a benign vascular neoplasm histologically simulating angiosarcoma, is newly recognized and has been described primarily in the genitourinary tract. Here, we present a case of renal anastomosing hemangioma originating in the left kidney of a 32-year-old Chinese man with detailed computerized tomography (CT) and enhanced CT image information. The patient had no obvious signs and symptoms. The tumor was incidentally found by color Doppler imaging during a routine heath check-up. Subsequently, a detailed CT and an enhanced CT scan were performed. The tumor was well demarcated, and mahogany brown lesions, which measured 2.6 cm in maximum diameter, were observed. Microscopically, the tumor shows a lobular architecture with alternating cellular areas composed of anastomosing sinusoidal capillary-sized vessels lined by hobnail endothelial cells and edematous, hyaline paucicellular areas. Cytologically, the tumor cells were generally bland and exhibited positivity for CD31 and CD34 immunohistochemically. The patient had good status without evidence of tumor recurrence 21 months after the surgery. We suggest that more attention should be focused on this rare renal hemangioma variant and that it should not be over-diagnosed as a malignance, particularly an angiosarcoma.