MYOFIBROBLASTOMA OF THE BREAST REVISITED - AN ETIOLOGIC ASSOCIATION WITH ANDROGENS

Myofibroblastoma of the breast is an uncommon benign stromal tumor enc ountered predominantly among elderly men. Histologically, myofibroblas toma is a well circumscribed tumor comprised of bipolar spindle cells arranged in short fascicles traversed by collagen bundles. Eased on pr evious histological, immunohistochemical, and ultrastructural observat ions, this tumor is thought to be derived from myofibroblasts. The pat hogenesis df myofibroblastoma is unknown. Given the demographics of th is lesion, the established trophic effect of steroid hormones, and the potential diagnostic utility of hormone receptor analysis in differen tiating spindle cell tumors, we immunohistochemically tested for estro gen and androgen receptors in a host of spindle cell lesions including myofibroblastoma of the breast Five cases reported herein of histolog ical confirmed myofibroblastoma obtained from male and female breasts each showed strong nuclear antibody staining fdr the androgen receptor , not seen in four cases of leiomyosarcoma, three cases of fibromatosi s, three cases of dermato-fibrosarcoma protuberans, and two cases of m onophasic synovial sarcoma. We postulate that the androgen receptor or its ligands may be pathological,ly related to the development of myof ibroblastoma of the breast and diagnostically useful in differentiatin g it from other spindle cell lesions. Copyright (C) 1998 by W.B. Saund ers Company.