Das immunhistochemische Profil metaplastischer Mammakarzinome unter besonderer Berücksichtigung muskulärer und myoepithelialer Marker

p63, a member of the p53 gene family, is involved in cellular differentiation and is expressed in the nuclei of myoepithelial cells of normal breast ducts and lobules. Although p63 has been recently reported to be expressed in sarcomatoid/metaplastic carcinoma of the breast, in addition to ist role as a myoepithelial marker, its expression pattern in breast carcinomas and sarcomas has not been fully characterized, and its potential diagnostic utility has not been defined. A large series of 57 metaplastic carcinomas, including cases with typical large-cell squamous carcinomas, pure spindelcell desmoplastic carcinomas, spindlecell-angiomatoid-squamous carcinomas, high differentiated adeno-squamous carcinomas, solid pleomorphic and giantcellular carcinomas, spindlecell myoid metaplastic carcinomas and chondroid-matrix-producing carcinomas, were evaluated for their immunohistochemical profile. p63 expression with respect to the different cellular components was assessed. Using p63 for diagnosis of metaplastic carcinoma gives a sensitivity of 70%. p63 may be used as an adjunct marker in the diagnosis of metaplastic carcinoma. We propose the inclusion of p63 as part of the diagnostic workup of challenging spindle cell tumors of the breast as a highly specific marker for metaplastic carcinomas.