Poorly differentiated myoepithelial cell rich carcinoma of the breast

Three unusual cases of invasive breast carcinoma are reported, each comprising a dual malignant cellular proliferation consisting of 'ordinary' epithelial cells as well as myoepithelial cells haphazardly intermingled. The cases displayed features which did not match any of the four main types of invasive malignant breast tumours containing myoepithelial elements, i.e. adenomyoepithelioma, adenoid cystic carcinoma, pure myoepithelioma and low-grade adenosquamous carcinoma. The designation of 'poorly differentiated myoepithelial cell rich carcinoma' (PDMC) is proposed for these tumours.