[A case of carcinoma of the breast with squamous and cartilaginous metaplasia].

A 40 year-old female underwent mastectomy for a rapidly growing left breast mass. Histologically, the tumor was composed of invasive ductal carcinoma with squamous metaplasia, a cartilaginous component and a pleomorphic sarcoma-like component. In each histologic feature, gradual transition was recognized. A diagnosis of carcinoma with metaplasia (squamous and cartilaginous type) of the breast was made. The cartilaginous component in this case is probably the result of direct cartilaginous metaplasia of carcinoma cells and cartilaginous metaplasia followed upon carcinoma cells into small undifferentiated tumor cells and pleomorphic sarcomatous cells.