METAPLASTIC CARCINOMA OF THE BREAST - REPORT OF 3 CASES

BACKGROUND. Metaplastic carcinoma is a rare form of breast carcinoma t hat often is confused with other benign and malignant entities. The di agnosis can be difficult to establish on both a clinical and conventio nal histopathologic basis. One report recently described clinical and mammographic features dissimilar to the authors experience but to the authors' knowledge no other reports have been published. Therefore a r eview of three cases was undertaken; all patients had undergone mammog raphy to identify and report the mammographic features of this disease , suggesting that imaging may add to the proper diagnosis of this enti ty. METHODS, Three clinical cases in which the diagnosis of metaplasti c carcinoma was confirmed and for which mammography was performed were reviewed retrospectively. Follow-up on all three patients was availab le. RESULTS. Metaplastic carcinoma may be manifest as a well circumscr ibed mass or an irregular or spiculated mass. The latter always is hig hly suspicious for malignancy and the former incurs suspicion if it gr ows, although in this series the smooth mass was biopsied immediately. The spiculated masses were associated with delayed diagnosis and poor er prognosis because immunohistochemical studies were not performed on the original excisional biopsy specimens. CONCLUSIONS. Although spicu lated masses usually are associated with invasive ductal and lobular c arcinoma, they also may represent metaplastic carcinoma and immunohist ochemical studies often are required to establish this diagnosis and a void delay ill proper treatment. Well circumscribed masses representin g this disease may suggest benign disease but metaplastic carcinoma sh ould be included in the differential diagnosis, especially if the mass enlarges. (C) 1998 American Cancer Society.