SPINDLE-CELL CARCINOMA OF THE BREAST, A MIMICKER OF BENIGN LESIONS - CASE-REPORT AND REVIEW OF THE LITERATURE

The clinical and pathologic features of a breast tumor with unusual mo rphology in a 69-year-old woman are presented. Spindle cell carcinoma is considered one of the variants of metaplastic carcinoma and is comm only described in the upper aerodigestive tract, but it is relatively rare in the breast. This case is uniquely different from the usual cas es of spindle cell carcinoma because of the lack of squamous different iation or a recognizable infiltrating ductal component at the light mi croscopic level. With immunohistochemical stains using keratin and act in, a rather prominent network of infiltrating compressed ductal struc tures became apparent. These immunohistochemical features are consiste nt with the current concept of myoepithelial origin for metaplastic ca rcinomas. Although mention has been made in the literature of cases in which this ''bland'' carcinoma could be confused with benign nonneopl astic conditions, few illustrated examples exist. The prognosis for th is particular subgroup of metaplastic carcinoma may be somewhat better than that for ordinary ductal carcinoma. For prognostic purposes, thi s entity should be distinguished from other metaplastic carcinomas and sarcomas, but more importantly, it should be differentiated from lesi ons such as nodular fasciitis, reactive granulation tissue, and fibrom atosis, with which it may be confused histologically.