Selective cryolysis: a novel method of non-invasive fat removal.

BACKGROUND AND OBJECTIVES Excess fat poses a host of local and systemic problems. Various energy sources, for example, laser, ultrasound, and radiofrequency electric current have been studied as potential non-invasive treatments aimed at local destruction of subcutaneous fat. Cryosurgery at very low temperatures is routinely used for non-specific tissue destruction, however the potential for tissue-specific cold injury has not been investigated. This study describes non-invasive cold-induced selective destruction of subcutaneous fat. MATERIALS AND METHODS Black Yucatan pigs under general anesthesia were exposed within test sites to preset temperatures of 20, -1, -3, -5, and -7 degrees C for 10 minutes. Gross and histological assessments were performed immediately, 1 day, 2, 7, 14 and 28 days post-cold exposure for four pigs, and up to 3.5 months for one pig. Additionally, six pigs were exposed between -5 degrees C and -8 degrees C for 10 minutes, at sites covering approximately 15% body surface area, followed by serum lipid level determinations at various time points up to 3 months. RESULTS A lobular panniculitis was induced by cooling, followed for some test sites by grossly obvious loss of several mm of subcutaneous fat occurring gradually during the 3.5 months study period. Loss of adipocytes, the appearance of lipid-laden mononuclear inflammatory cells, and local thickening of fibrous septae were noted. Typically there was no clinical or histological evidence of injury to skin, and no scarring. Serum lipids were not significantly increased. CONCLUSIONS Prolonged, controlled local skin cooling can induce selective damage and subsequent loss of subcutaneous fat, without damaging the overlying skin. Selective cryolysis warrants further study as a local treatment for removal of adipose tissue.