Cytophotometric measurements of metaplastic carcinoma of the breast: correlation with pathologic features and clinical behavior.

The DNA content of the various neoplastic elements of 12 Feulgen-stained metaplastic breast carcinomas was measured by image analysis. Spindle cell, osseous, chondroid, rhabdomyoid, or squamous cell metaplastic elements comprised at least half of each neoplasm in which an invasive ductal carcinoma component also was identified. The epithelial elements in all of the neoplasms were aneuploid, as was the metaplastic component in 11 of the cases. Multiple stem cell lines were detected in the ductal carcinoma component in 4 cases and in the metaplastic components in 5 cases. Our findings lend support to the view that metaplastic elements are derived from malignant epithelial cells, rather than from benign stromal cells. Neither aneuploidy nor the presence of multiple stem cell lines was a useful predictor of the biologic behavior of these 12 neoplasms.