Fat necrosis is a rare lesion of the breast but is of clinical importance because it produces a mass (often accompanied by skin or nipple retraction) that is usually indistinguishable from carcinoma even with imaging studies. Fat necrosis can occur after trauma; after fat injections to augment breast size or fill defects after breast surgery; and after segmental resection, radiation therapy, or flap reconstruction following mastectomy.
The resultant mass may be confused with cancer. If untreated, the mass gradually disappears. If imaging is not typical of fat necrosis, the safest course is to obtain a biopsy. Core needle biopsy is usually adequate.
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