To predict if antiestrogenic agents are useful in the treatment of breast fibromatoses, we undertook an immunohistochemical study of sex steroid hormone receptors (estrogen receptor, progesterone receptor, and androgen receptor) and protein pS2 in 33 cases.
The morphologic and immunohistochemical findings were correlated to patient menstrual status, which was categorized as childbearing age (n = 15), perimenopausal (n = 8), and postmenopausal (n = 10).
Fibromatoses in women of childbearing age were more cellular, more mitotically active, and displayed a larger proportion of cells with mild atypia than those in perimenopausal and postmenopausal women. The hormonal status of these 3 groups does not explain the morphologic variations observed in these groups, inasmuch as no immunostaining for any of the hormone receptors was detected in the tumors.
The absence of estrogen receptor and pS2 in breast fibromatoses suggests that antiestrogenic agents are unlikely to be beneficial in the management of these tumors. Assessment of the hormone receptor profile is a useful adjunct in the diagnosis of spindle cell lesions of the breast. Although most spindle cell carcinomas as well as fibromatoses of the breast do not express estrogen or progesterone receptors, the absence of androgen receptor reactivity would favor a diagnosis of fibromatosis over that of myofibroblastoma.