Membranous fat necrosis due to subcutaneous elemental mercury injections.

Membranous fat necrosis (MFN) is a distinct abnormality in systemic and subcutaneous fatty tissue. Although ischemia and trauma have been implicated in its causation, the exact pathogenesis of MFN remains unknown. The deposition of metallic mercury in subcutaneous tissue due to accidental penetration or deliberate injection of mercury is unusual. Depending on the duration of the deposition, localized necrosis, suppuration, and granuloma formation have been described at mercury injection sites. We report subcutaneous MFN, a hitherto unrecognized histopathologic phenomenon at sites of mercury deposition, in a 21-year-old soccer player who had deliberate subcutaneous and intramuscular elemental mercury injections to improve his sporting performance.