Fat necrosis of the breast.

Fat necrosis of the breast is an uncommon entity but may mimic malignancy on both mammographic and clinical examination. Seven patients had recent excisional breast biopsy specimens that showed fat necrosis. The mammographic appearance is a reflection of the reparative phase of the lesion, with a cystic appearance representing early or incomplete healing. Progression to connective tissue invasion appears as an irregular, dense, spiculated mass. Clinically, these tumors may be firm, fixed, and produce overlying skin or nipple retraction. No matter how strong the clinical suspicion that a breast lesion represents fat necrosis, an excisional biopsy is necessary for confirmation in all cases.