Myofibroblastoma of the breast with smooth muscle differentiation showing deletion of 13q14 region: report of a case.

Breast myofibroblastomas are rare benign mesenchymal tumors belonging to the group of stromal breast tumors composed of spindle-shaped cells and characterized by a broad morphologic spectrum. Among the different morphologic variants described, breast MFBs can show smooth muscle cell differentiation in very rare cases. In terms of the genetic abnormalities found in this type of tumor, a deletion of chromosome 13q14 was recently confirmed by FISH in some cases of mammary MFB. In this paper, we report an unusual case of MFB with smooth muscle differentiation showing a deletion of chromosome 13q14.