Malignant phyllodes tumors of the breast associating malignancy of both mesenchymal and epithelial components (invasive or in situ ductal carcinoma)

Phyllodes tumors of the breast are biphasic tumors consisting from an epithelial component and a mesenchymal component. Usually, the mesenchymal component of the tumor is the one who dictates the malignancy of the biphasic proliferation. Presence of the malignancy of the both, epithelial [under the form of invasive carcinoma or ductal carcinoma in situ (DCIS)] and mesenchymal components is very rare. Most of the data available from the literature refers to single case presentations. This paper presents the experience of Prof. Dr. Ion Chiricuţă Oncological Institute (IOCN), Cluj-Napoca, Romania, with the malignant phyllodes tumors with both epithelial and mesenchymal components showing malignancy. Over two decades (1999–2018), four cases of malignant phyllodes tumors with concomitant epithelial and mesenchymal malignancy were found and presented as a case series. Two out of four cases were malignant phyllodes tumors harboring invasive breast carcinomas (one case with associated DCIS and one case of pure invasive carcinoma) and two cases were malignant phyllodes tumors with the epithelial component showing DCIS. Average follow-up period was 67 months (from 39 to 132 months) with a disease-free survival of 58 months.