Mammary myofibroblastoma is a benign spindle cell neoplasm of stromal myofibroblasts. It is typically composed of bland, slender spindle cells which are arranged in fascicles or cohesive clusters, with intervening thick collagen bundles. The cells have abundant, clear to grey cytoplasm, and nuclear atypia and mitotic activity are generally absent. A pushing, lobulated growth pattern is classic. This particular lesion demonstrates elongated cell groups and collagen bundles. Admixed benign adipose tissue is also seen.
This tumour was from an elderly man and was located in a subcutaneous location.
In its conventional form, this lesion is readily diagnosed by H&E alone.
This slide shows CD34 stain, see related content for H&E, desmin, and ER stains.
See Related Content for references:
Gaetano, M. Arch of Path & Lab Med: November 2008, Vol. 132, No. 11, pp. 1813-1820.
Hodgson, A., Chang, M. Breast, Myofibroblastoma, CD34 stain. Digital Laboratory Medicine Library, Dept of Laboratory Medicine & Pathobiology, University of Toronto. Published
. Accessed December 17, 2025. https://dev.dlml.cflabs.ca/image/breast-myofibroblastoma-cd34-stain-lmp20495
