[835] Anastomosing Hemangioma of the Genitourinary Tract: A Previously Undescribed Lesion Mimicking Angiosarcoma

E Montgomery, JI Epstein. Johns Hopkins Hospital, Baltimore

Background: We describe six cases of a previously unrecognized vascular neoplasm that can simulate angiosarcoma.
Design: Cases of a novel rare vascular tumor with a proclivity for the genitourinary tract encountered in our consultation material were prospectively collected between 1999 and 2008. Follow-up information was obtained when possible.
Results: There were six tumors from 4 men (66%) and 2 women, ranging in age from 49-75 years (median, 59.5) involving the kidney and renal hilum (4, 66%) and testis (2). Tumors ranged from 1.3 - 1.7 cm (median 1.6 cm) and were grossly well-marginated with a hemorrhagic mahogany spongy appearance. Microscopically, at low power they had a loosely lobulated architecture and were associated with a medium-caliber vessel (5/6, 83%). Most kidney (3/4, 75%) tumors showed minor extensions into adjacent adipose tissue. At higher magnification, the tumors consisted of interanastomosing sinusoidal capillary-sized vessels with scattered hobnail endothelial cells within a framework of non-endothelial supporting cells. There was a minimal inflammatory backdrop consisting of lymphocytes but not plasma cells or acute inflammation. Mitoses were absent (5/6, 83%) or rare (1 case; in supporting cells). There was mild cytologic atypia in one of the cases but no multilayering of endothelial cells in any case. Vascular thrombi were typical (5/6, 83%) and the lesions had zones of central infarction with variable sclerosis (5/6, 83%). Two (33%) tumors featured prominent extra-medullary hematopoiesis and two (33%) had striking hyaline globules reminiscent of those seen in Kaposi's sarcoma. Imunohistochemistry was available on some cases and the lesions stained with CD34, CD31, and FVIII but not keratin AE1/3, EMA, HMB45, PLAP, or HCG. In all but one submitted consultation, the possibility of angiosarcoma had been raised based on the anastomosing vascular pattern. On follow-up, there were no recurrences or metastases in 4 cases (range 5 - 36 months; median 12 months), one patient was lost to follow-up and the last was a recent case.
Conclusions: Anastomosing hemangioma of the genitouninary tract is a rare neoplasm displaying some overlapping features of both sinusoidal hemangioma and hobnail hemangioma of soft tissue and skin. However, in our opinion, it is a unique neoplasm with a proclivity for the kidney. Its anastomosing appearance can lead to concern for angiosarcoma but, despite small numbers and limited follow-up in our series, evidence to date supports that the lesion is benign.
Category: Genitourinary (including renal tumors)

Monday, March 9, 2009 2:15 PM

Platform Session: Section A, Monday Afternoon