Background Paradoxical adipose hyperplasia (PAH) is a rare, moderate-to-severe adverse event associated with cryolipolysis (CoolSculpting, CS). Objectives The aim of this study was to describe the incidence, diagnosis, and treatment of PAH occurring after CS for nonsurgical fat reduction. Methods A multicenter evaluation of all patients who underwent CS treatment between January 2015 and December 2019 at 8 Canadian medical centers was conducted. Data abstracted included symptoms, management

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... tegy, outcome, operator characteristics, device characteristics, patient characteristics, body region, and CS treatment details. Incidence of PAH was calculated based on the number of treatment cycles. Results Our findings revealed incidence rates between 0.05% and 0.39%, which are slightly higher than the manufacturer's quoted rate of 0.025% (1 per 4000 cycles). Incidence rates at all sites were dramatically reduced by over 75% with the implementation of newer models of CS units. Of patients who developed PAH, 55% were male and 77.8% were of European ethnic origin. The majority of cases (76.9%) were associated with older models of CS units. Conclusions Development of PAH may be related to a combination of factors, including older models of CS units and applicators, as well as individual characteristics that predispose certain patients. Level of Evidence: 4