Paradoxical adipose hyperplasia secondary to cryolipolysis: An underreported entity?

Background and Objective Cryolipolysis is a non-invasive, safe, and effective treatment for localized fat reduction. Paradoxical adipose hyperplasia (PAH) is a rare adverse effect in which patients develop painless, firm, and well-demarcated tissue masses in the treatment areas approximately 3-6 months following cryolipolysis. The incidence of PAH has been estimated at 0.0051% or 1 in 20,000 treated patients. We report two cases of PAH seen in our practice, which may suggest the incidence is greater than previously reported. Study Design/Patients and Methods A 44-year-old man underwent cryolipolysis for unwanted fat in the pectoral region. At 4 month follow-up, the patient had well-demarcated tissue growth in the treatment areas. He elected to undergo additional cryolipolysis treatment to the areas. Two months later, he was found to have further tissue growth in the treatment areas. The patient then underwent corrective treatment with liposuction. A 52-year-old man underwent cryolipolysis for unwanted lower abdominal fat. At one year follow-up, he had a well-demarcated, subcutaneous mass on the lower abdomen corresponding to the treatment site. The patient elected to undergo corrective treatment with liposuction. Adipose tissue samples from the treated and non-treated areas, for control, were collected, processed, and stained to evaluate cellularity and tissue structure. Results In our practice, the incidence of PAH is 0.47% or 2 in 422 cryolipolysis treatments. This is 100 times greater than the device manufacturer's reported incidence. Histopathologic examination of the subcutaneous tissue mass showed an increased number of adipocytes, fibrosis, and scar tissue in the treated areas when compared to controls. No lipoblasts, a marker of malignant neoplastic proliferation, were identified on the histopathologic examination of the affected tissues. Conclusion The incidence of PAH is likely underreported. Further investigation is necessary to elucidate its mechanism of action. By understanding the pathogenesis, this rare adverse effect may be avoided, or even utilized as a therapeutic alternative for the treatment of congenital or acquired lipodystrophy. Lasers Surg. Med. 47:476-478, 2015.