[97] Hemangioendothelioma and Angiosarcoma of Bone: Distinct Histological Criteria Predicting Clinical Behavior

SL Verbeke, F Bertoni, P Bacchini, R Sciot, BJ Mertens, HM Kroon, PC Hogendoorn, JV Bovee. Leiden University Medical Center, Leiden, Netherlands; Rizzoli Institute, Bologna, Italy; University Hospitals, Leuven, Belgium

Background: Vascular tumors of bone are rare and represent less than 1% of the primary malignant bone tumors. Today, angiosarcoma is the most accepted term for obvious high-grade tumors. However, the existence of an intermediate category is controversial and not recognized by the 2002 WHO classification.
Design: We studied 80 vascular tumors of bone (74 patients), other than hemangioma of bone, diagnosed between 1964 and 2007. All clinical, radiological, and patologicl data were reviewed. Different immunohistochemical and morphological parameters were assessed and related to outcome.
Results: Tumors were positive for CD31 in 67/71 (94%), CD34 in 38/73 (53%), von Willebrand Factor (vWF) in 58/71 (82%), and keratin in 51/73 (70%), although only 18 showed epithelioid phenotype. Multivariate analysis identified two prognostic groups. Group I, in which the combination of a macronucleolus, 3 or more mitoses per 10 high-power field (HPF) and absence of an eosinophilic infiltrate predicted poor prognosis (death within 18 months). This group represents angiosarcoma of bone. Group II, with a better prognosis (5-year survival of 82.3% and metastatic rate of 8.1%), was characterized by the presence of several small nucleoli, less than 3 mitosis per 10 HPF and the presence of an eosinophilic infiltrate. Group II represents the intermediate category and is therefor best labeled as hemangioendothelioma of bone.
Conclusions: CD31 and vWF are sensitive markers to diagnose vascular tumors of bone. Since keratin positivity is seen in 70%, pathologists should avoid misinterpreting them as metastatic carcinoma. We report well defined histological criteria to distinguish two risk groups of vascular tumors of bone with a significantly different clinical course: I. angiosarcoma of bone, and II. hemangioendothelioma of bone as a category intermediate between hemangioma and angiosarcoma.
Category: Bone & Soft Tissue

Tuesday, March 10, 2009 9:30 AM

Poster Session III # 4, Tuesday Morning