Diagnostic problems in fine needle aspiration cytology of fat necrosis within a subcutaneous lipoma

Abstract

Fat necrosis in subcutaneous lipomas is very unusual and has been reported only occasionally. Literature regarding fine needle aspiration cytology of such a lesion is lacking although fat necrosis is well described in the breast. We came across a case of a large subcutaneous lipoma in the anterior abdominal wall with a well encapsulated area of fat necrosis. The aspiration smears showed an unusual picture which was misinterpreted as the fragments of the hydatid cyst wall. They were actually enlarged, nonnucleate, single adipocytes showing laminations, along with calcification and paucity of inflammation. Histopathology confirmed the diagnosis of fat necrosis within the lipoma. Such lesions can be mistaken on radiology for malignancy.