Fat necrosis may sometimes present as a palpable mass, which may raise clinical concern or distress in the patient.  Approximately 1/2 of cases have a history of trauma.  Fat necrosis is also a common finding in excision specimen after a preceding biopsy.

The characteristic findings of fat necrosis include mixed inflammation (neutrophils, histiocytes, etc.), fibroblastic proliferation, and liquefactive fat necrosis.  Each of the component may vary in prominence.  The most important thing is not to mistake fat necrosis for malignancy, and not miss an area of malignancy masked by fat necrosis (AE1/AE3 or CAM5.2 may be helpful in such situations).

Photomicrographs

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