Endoglin: An Adjunct Diagnostic Marker To Differentiate between Benign and Atypical Vascular Lesions/Proliferations Arising in the Breast Post-Radiation therapy
William Dubinski, Danny Ghazarian. University Health Network, Toronto, Canada
Background: Vascular lesions that arise in the breast following lumpectomy and radiation for breast carcinoma range from benign (e.g. telangiectasias) to atypical vascular lesions/proliferations (AVLPs) to angiosarcomas. Differentiating benign vascular proliferations from AVLPs by morphology is challenging and highly significant, as some AVLPs may progress to angiosarcoma.
Endoglin (CD105) is a specific marker of neovascularisation and differs from traditional panendothelial markers (e.g. CD34, CD31) in that it distinguishes newly formed (e.g. neoplastic) blood vessels from established 'bystander' vessels. Endoglin expression has been reported to be prognostically significant in various tumor types. We present the first comparison of endoglin immunohistochemical expression in benign vascular proliferations, AVLPs, and post-radiation angiosarcomas and apply our findings to differentiate between these lesions.
Design: Patients treated at University Health Network from 2001-2011 with a diagnosis of AVLP (5 cases) or post-radiation angiosarcoma (16 cases) were entered into the study. Each tumor and adjacent normal skin (21 cases) underwent immunostaining for endoglin and D2-40 and an expression value (positive or negative) was determined for each case. Cases were considered positive if any intensity of endoglin staining was present. A selection of benign vascular proliferations (3 pyogenic granulomas, 2 hemangiomas) was stained for comparison.
Results: The full spectrum of tumors was present, including benign proliferations, AVLPs, and both low- and high-grade angiosarcomas. Endoglin highlighted the endothelial cells of all benign vascular proliferations (2/2 hemangiomas, 3/3 pyogenic granulomas, p = 0.001). A complete lack of endoglin expression was observed in endothelial cells of all cases of AVLP and angiosarcoma (5/5 and 16/16 cases, respectively; p = 0.001). There was no endoglin expression in normal non-tumor skin (21/21 cases, p = 0.001). Endoglin did not highlight any lymphatic vessels in either tumor or normal skin.
Conclusions: Benign vascular proliferations retained endoglin expression whereas AVLPs and angiosarcomas showed a complete lack of endoglin expression in both the neoplastic vessels and tumor cells. Our data suggest that endoglin (CD 105) might be used as an adjunct diagnostic marker to differentiate between benign vascular proliferations and AVLPs and implies a new way to understand the contribution of endoglin in the pathogenesis of vascular proliferations.
Tuesday, March 20, 2012 9:30 AM
Poster Session III # 23, Tuesday Morning