Myoid Hamartoma of the Breast

A myoid hamartoma is a rare benign breast lesion that is considered to be a variant of mammary hamartoma. This lesion has an uncertain origin, likely in blood vessel walls, muscularis mammillae of the areolae, and mainly in myoepithelium. The tumor is well defined, with variable radiodensity under mammographic examination. However, the sonographic characteristics of this tumor have rarely been described. This report describes the sonographic features of a myoid hamartoma in the breast of a 56-year-old female. The tumor was oval shaped and compressible. Additionally, the tumor had heterogeneous echotexture, smooth margin, a thin echogenic capsule, and enhanced through-transmission.