Lipomatous tumors of the breast: A contemporary review.

Breast tumors with lipomatous or liposarcomatous components are infrequently encountered, but can be a source of diagnostic difficulty if the context of the fatty differentiation is not recognized. Among the true adipocytic tumors, lipoma is the most common lipomatous tumor arising in the breast. Several mammary spindle cell tumors may show adipocytic differentiation, including fibroepithelial tumors and myofibroblastoma. Liposarcomatous components most often arise in malignant phyllodes tumors, as opposed to primary liposarcomas of the breast which are believed to be uncommon. This article will review the spectrum fat-containing tumors of the breast with an emphasis on differential diagnosis and insights from recent molecular studies.