[721] Primary Vascular Tumors of the Kidney: A Clinicopathologic Analysis of 26 Cases

JG Brown, MB Amin, P Rao, AJ Lazar, GP Paner, R Gupta, JC Cheville, AL Folpe. Cedars-Sinai Medical Center, Los Angeles, CA; MD Anderson Cancer Center, Houston, TX; Loyola University Medical Center, Maywood, IL; Mayo Clinic, Rochester, MN

Background: Vascular tumors of the kidney are distinctly rare, and to date no large series has been reported. We analyzed a large series of primary vascular tumors of the kidney in order to further delineate their clinicopathological features and identify organ-specific morphologic features, if present.
Design: 26 renal cases previously coded as hemangioma, hemangioendothelioma and angiosarcoma were retrieved from our archives and re-evaluated histologically. Tumors were classified according to the 2000 WHO classification of tumors of soft tissue and bone. Clinical information was obtained.
Results: The tumors occurred in 17 males and 7 females (M:F = 2.4:1) ranging from 21 to 95 years (mean 57.4 years). Lesions ranged from 0.4 to 30 cm (mean 6.0 cm) and were tan-brown, cystic and hemorrhagic. On re-review, cases were classified as arteriovenous malformation (AVM, N=3), capillary hemangioma (CH, N=15) and angiosarcoma (AS, N=8). AVM were identical to their somatic soft tissue counterparts. Renal CH typically lacked a well-formed lobular pattern and showed a sieve-like arrangement reminiscent of the splenic sinusoids; all were non-infiltrative and lacked cytological atypia and mitotic activity. AS were diffusely infiltrative with extensive parenchymal destruction; all showed at least small areas of conventional vasoformative growth, but were frequently dominated by spindled and epithelioid histologies. All cases were positive for some combination of CD31, CD34, Fli-1, GLUT-1 and D2-40. Cytokeratin expression was absent in all AS. Follow-up was available for 14 cases: all patients with AVM and CH were disease free; 4 patients with AS were dead of disease at 1 mo, 1 mo, 6 mos and 11 mos, respectively.
Conclusions: Unlike in somatic soft tissue, where benign vascular tumors greatly outnumber malignant ones, a very significant number (31%) of renal vascular tumors are AS, with a very poor prognosis. Capillary hemangiomas of the kidney are morphologically distinctive tumors that often show spleen-like features, differing from their somatic soft tissue counterparts. In well-differentiated vascular lesions, renal cell carcinoma with angiomatoid growth, and in poorly-differentiated lesions, sarcomatoid renal cell carcinoma enter into the differential diagnosis.
Category: Genitourinary (including renal tumors)

Monday, March 9, 2009 9:30 AM

Poster Session I Stowell-Orbison/Autopsy Award # 113, Monday Morning