SAN DIEGO – Clinicians who perform cryolipolysis should inform patients about the risk of paradoxical adipose hyperplasia, “a newly described, rare side effect” consisting of a “usually permanent” increase in fatty tissue at the treatment site, said Dr. Andrew Nelson, a dermatologist in private practice in St. Petersburg, Fla.
Based on case reports to date, the estimated incidence of paradoxical adipose hyperplasia (PAH) is only about 0.0051%, or 1 case per 20,000 treatment cycles, Dr. Nelson added. But use of cryolipolysis is growing rapidly, including use among physician extenders, he noted. “We should be counseling all our patients on the possibility of PAH, and we need to generate more data to determine its cause and the best treatment options.”
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Adipose hyperplasia is a rare side effect of cryolipolysis.
Even a single cycle of cryolipolysis can trigger PAH, which seems to occur at least 2-3 months later and requires invasive treatment to resolve, Dr. Nelson said at the annual meeting of the American Society for Dermatologic Surgery (ASDS). “Most patients report an initial reduction of fat before PAH develops,” he added.
Histology at the site of PAH typically shows disorganized adipocytes that vary more in size and shape than does normal panniculus, but the overlying dermis and epidermis appear normal. About half of cases reported to date have involved men, “but women are treated at a higher rate than men, so there may be a preponderance of men,” he said.
No one knows why PAH occurs, Dr. Nelson noted. Possibilities include recruitment of local or circulating preadipocytes or stem cells; changes in the expression of receptors or soluble factors that play a role in adipocyte metabolism; reduced sympathetic innervation; and hypoxic injury, he said. Hypoxic injury is known to spur capillary growth, which can cause fat hypertrophy, he added.
In a case reported at the ASDS meeting by Dr. Brian Raphael, a 75-year-old woman developed PAH approximately 4 months after undergoing two sessions of cryolipolysis that had been spaced 1 month apart. The adipose tissue had accumulated in the center of the treatment site “in a distribution identical to the device applicator,” Dr. Raphael and his associates reported. They performed a wedge biopsy to confirm that the fat accumulation was benign, and then carried out a pannectomy to remove the unwanted fat, they said.
Cryolipolysis works by slowly cooling adipocytes, which are more sensitive to temperature decreases than epidermal and dermal cells, Dr. Nelson said. The adipocytes crystallize, which is thought to trigger their apoptosis and gradual elimination from the body in the months after treatment. Adverse effects besides PAH are usually mild and include edema, pain, and temporary redness at the treatment site, he noted. About two-thirds of patients also have a temporary, localized loss of sensation that can last up to 8 weeks, he added.
Dr. Nelson and Dr. Raphael reported no conflicts of interest.