Myoid hamartoma of the breast with focal chondromyoxid metaplasia and pseudoangiomatous stromal hyperplasia: A case report.

Hamartomas of the breast, also known as fibroadenolipomas, lipofibroadenomas or adenolipomas, are benign lesions. Hamartomas account for between 0.04 and 1.15% of all benign breast tumors in females. Myoid hamartoma of the breast (MHB) is extremely rare. The present study describes a case of MHB in a 44-year-old female. Screening mammography revealed a lobulated partial indistinct isodense mass measuring ~3.8 cm in the upper outer quadrant of the left breast. Sonographic examinations revealed a 2-3-cm mass in the left breast, which was fairly well circumbscribed and demonstrated complex scattered echogenic areas and isoechoic tissue. A core needle biopsy demonstrated fibrocystic changes, with small focal ductule aggregations. As malignancy could not be excluded, a partial mastectomy was performed using a circumareolar incision. The mass was histopathologically diagnosed as MHB with focal chondromyoxid metaplasia and pseudoangiomatous stromal hyperplasia. The histological diagnosis was based upon the findings of the well-circumscribed tumor, which was composed of entrapped mammary ducts, fat cells and myoid stromal components, with focal chondromyxoid metaplasia and pseudoangiomatous stromal hyperplasia. The tumor cells exhibited diffuse cluster of differentiation 34-positive immunoreactivity, which was consistent with a diagnosis of pseudoangiomatous stromal hyperplasia.