Myoid Hamartoma: An Exceptionally Rare Breast Lesion

Breast hamartomas (BH) account for 3.9-4.8% of all breast tumors. The myoid or the muscular variant, Myoid Breast Hamartoma (MBH) is exceptionally rare with less than 30 reported cases in the English medical literature. This paper reports a case of MBH in 53year old female who presented with 6-year-old left breast lump which has been gradually increasing in size. Clinically, the mass was suggestive of a fibroadenoma; however, microcalcifications on ultrasonography were an indication for further investigation with Fine Needle Aspiration Cytology (FNAC). Cytologically, the yield was in favor of a fibroadenoma. Lumpectomy was performed without any complication and the mass was finally diagnosed as MBH histopathologically. The histologic diagnosis was based on the findings of predominant stromal smooth muscle bundles (proved by immunohistochemistry) along with scattered intact terminal duct-lobular units, dilated ducts and entrapped islands of mature fibroadipose tissue.