Myofibroblastoma of the male breast: A case report

Abstract Myofibroblastoma (MFB) is a rare spindle stromal tumour of the breast that predominates in 60–80 years-old adult males. Its imaging features are nonspecific, leading to misdiagnosis. Thus, core biopsy is needed for definitive diagnosis. Macroscopically, MFB is usually a well-circumscribed, firm and rubbery, unencapsulated, pale white to grey round mass. Microscopically, it consists on spindle cells arranged in haphazardly intersecting fascicles or clusters, thick hyalinized collagen bundles and low mitotic activity with a lack of myoepithelial component and necrosis. Immunohistochemistry shows consistently positive immunoreactivity to vimentin and CD34, while expression of desmin, SMA, bcl-2 and CD99 varies. Oestrogen, progesterone and androgen receptors are usually expressed. They are constantly negative to cytokeratins, EMA, S100 protein, HMB-45 and c-kit (CD117). These differentiate them from fibroadenoma , phyllodes tumour, round pattern gynecomastia, carcinoma and sarcoma , since they present infiltrative growth and are negative to CD34. Wide local excision is curative, with no need of sentinel lymph node biopsy, since local recurrence is extremely low and has been reported to be less than 1.5%. No distant metastases have been described on the literature. We report a rare case MFB on a 73-year-old male attended at our institution presenting with a nodule on the right breast.