Breast hamartoma is a rare benign tumor that comprises lobular breast tissues with various admixtures of fibrous, fibrocystic, and adipose tissue. Hamartoma accounts for 0.7%-5.0% of all benign breast tumors. Myoid hamartoma is an extremely rare variant of mammary hamartoma characterized by the presence of smooth muscle component. Herein, we report a case of myoid hamartoma showing irregular margins and microcalcifications with a literature review.