The importance of estrogen in vascular neoplasia is suggested by a predilection for women and a tendency for rapid growth during pregnancy. Although early experiments using radioligand assays demonstrated estrogen receptor (ER) expression, these findings were not confirmed by subsequent immunohistochemical studies which were performed with antibodies raised against ERa. A newly discovered estrogen receptor subtype, ERb, has not been previously characterized in vascular lesions. In order to verify the expression of estrogen receptors in vascular neoplasms as well as to clarify the inconsistency between radioligand and early immunohistochemical studies, we examined a series of 53 benign and malignant vascular neoplasms for ERb expression. All of the subtypes of vascular neoplasia examined had nuclear expression of ERb. The majority of cases (94%) displayed 2 þ to 3 þ staining. The discrepancy between radioligand studies and previous immunohistochemical studies is attributable to the use of antibodies raised against ERa, which is not expressed in vascular lesions, and not ERb, which is broadly expressed in both benign and malignant vascular neoplasms. Although ERb may be of limited diagnostic use in vascular neoplasia due to its broad expression, the potential exists for a therapeutic approach using ER agonists. The role of estrogen in vascular neoplasia has long been suspected due to the observation that vascular neoplasms tend to grow rapidly during pregnancy and in adolescence. 1 These clinical observations were initially substantiated by early experiments in the 1980s using radioligand assays, which confirmed the presence of the estrogen receptor (ER) in vascular tumors; 2,3 however, with the advent of immunohistochemical techniques, subsequent studies performed in the 1990s with antibodies raised against the ER refuted these earlier data and it appeared that the newer technology had exposed the limitations of the older biochemical assays. [4][5][6][7] Recently, an additional ER subtype, estrogen receptor beta (ERb), 8 was identified and the previous ER against which the original antibodies were raised was renamed estrogen receptor alpha (ERa). Although ERa has been assessed immunohistochemically in vascular neoplasms and found to be absent, ERb has not been previously characterized in these entities. In order to verify the expression of ER in vascular tumors as well as to clarify the inconsistency between radioligand and early immunohistochemical studies, we examined a series of 53 benign and malignant vascular neoplasms for ERb expression.
Materials and methodsIn all, 22 cases of angiosarcoma, three cases of Kaposi sarcoma, one case of epithelioid hemangioendothelioma, two cases of spindle-cell hemangioma, four cases of infantile hemangioendothelioma, 13 cases of hemangioma, seven cases of lymphangioma and one case of papillary endothelial hyperplasia were identified and retrieved from the paraffin archives of the University of Chicago. Formalin-fixed paraffin-embedded specimens were cut into 4-mm sections an...