Defining fat necrosis in plastic surgery.

BACKGROUND Fat necrosis is a well-known complication of free tissue transfer and fat grafting that is becoming increasingly reported in the literature. However, there is no clear consensus on how fat necrosis is defined and classified in the plastic surgery literature. METHODS A systematic review of the literature was performed using the PubMed database of the National Library of Medicine and National Institutes of Health and Google Scholar from January 1, 2003, to November 1, 2013. The keywords used in the search included "fat necrosis" and "plastic surgery." RESULTS Sixty-nine articles were chosen that met the authors' criteria and were included in this review. There was wide variation on the size requirements and postoperative timing when defining fat necrosis. In addition, the workup sought after clinical examination to confirm a diagnosis of fat necrosis varied, including radiographic studies, histopathologic examination, or a series of studies. CONCLUSIONS Based on the articles reviewed in this article, a more uniform definition needs to exist that is clearly defined in all articles that report on fat necrosis. The authors suggest defining fat necrosis as a palpable, discrete, and persistent subcutaneous firmness found postoperatively that measures at least 1 cm during physical examination. Fat necrosis can be identified and confirmed by imaging and histopathology or through intraoperative findings. The authors provide a classification system for fat necrosis that can be used by clinicians to describe fat necrosis into varying grades of severity to ultimately help guide clinical decision-making.