Monarch Disease Ontology identifier MONDO_0003990 (malignant breast myoepithelioma) is an invasive malignant tumor that arises from the breast. It is characterized by the presence of spindle-shaped myoepithelial cells. Mitoses are present. Rarely, local recurrences and distant metastases have been reported. Also known as: breast malignant myoepithelioma, breast myoepithelial carcinoma.