Carcinoma metaplásico de mama variante «productor de matriz». Expresión de CD99 y P63

The metaplastic carcinoma of matrix producing variant is positive for CD99 and it is the only subtype which expresses it. Therefore, it can be diagnostically useful, both in primary tumours and metastases. In this case, p63 expression is valuable in the differential diagnosis with other sarcomas and mixed tumours of the breast (fillodes tumour). This matrix-producing carcinoma shows a myoepithelial or basal phenotype in the metaplastic component and exhibits immunohistochemical differences from the epithelial component. The confirmation of a myoepithelial or basal component in the metaplastic carcinoma of matrix producing variant has important clinical and therapeutic implications.