Cryolipolysis treatment using the original cryolipolysis applicator requires treatment duration of 60 minutes, during which a fold of adipose tissue is suctioned by a negative pressure applicator consisting of two cooling plates at -10°C.9 Newer applicators and updated recommended treatment settings have since been released, achieving lower treatment temperature, reduced treatment time, decreased risk of bruising, one without suction, and greater patient satisfaction (Table 1).9,10 Published studies on cryolipolysis reported good safety and efficacy with minimal recovery time and visible ef- fects seen on average at 4 months post-treatment, which makes cryolipolysis an appealing treatment option for patients.11 Over the past several years, there have been increasing published reports and physician discussion regarding paradoxical adipose hyperplasia (PAH) post-cryolipolysis, previously identi ed as a "rare" adverse effect. PAH often clinically presents as a painless, firm, well-demarcated, visually appreciable enlarged tissue growth in the treatment area 3 to 9 months post-cryolipolysis. Herein, we review published reports of PAH post-cryolipolysis, expand on previously proposed hypothesis of PAH, and provide recommendations for prevention and treatment of PAH.
METHODS
We employed the following literature review search strategy: on July 26, 2016, we systematically searched the computerized medical bibliographic databases PubMed, EMBASE, Web of Science, and CINAHL with the search term "cryolipolysis" (see Figure 1 for schematic of literature search strategy based upon the Preferred Reporting Items for Systematic Reviews and Meta- Analyses [PRISMA] guidelines).12 The relevant records that met the following criteria were selected for inclusion: clinical reports of PAH post-cryolipolysis. Information on patient characteristics, anatomic locations, treatment settings, number of treatment ses-sions, time of PAH onset, histology or radiology assessments, and management of PAH of published reports were extracted from reviewed articles. Exclusion criteria included non-English articles. A Grade of Recommendation is not included in this sys- tematic review as PAH is an adverse effect post-cryolipolysis.
RESULTS
A total of 314 records were returned from our search terms. After removal of duplicates, 138 records were screened for titles, abstracts, and/or full-texts, and 10 records were found to be suitable for our review. These 10 records include 7 case series and/or case reports and 3 conference abstracts and are sum- marized in Table 2.3,13-21 We identified a total of 16 cases of PAH post-cryolipolysis in the published literature.
DISCUSSION AND FUTURE DIRECTIONS
Based upon the published literature, there is strong clinical evidence indicating PAH is an adverse effect associated with cryolipolysis as the adipose hyperplasia occurs at the treatment site, with a timeline of 3 to 9 months post-cryolipolysis, and no reports of any signi cant dietary or weight changes per patients with PAH. To date, there have been over 2 million cryolipolysis procedures performed worldwide.22 Based upon manufactur- er’s post-market consumer data and limited published reports, the incidence of PAH has been on the rise from 2013, 2014, and the second quarter of 2015 (0.0032%, 0.021-0.026%, and 0.025%, respectively).21,23 The most recent post-market consum- er data provided by the device manufacturer for 2016 shows the PAH incidence rate remains consistent with the previously published incidence rate of approximately 0.025%, or 1 in 4,000 treatment cycles.21 Post-market consumer data indicated that PAH has occurred in areas including the abdomen, anks, back, thighs, and chest, and may be associated with high vacuum set- tings and greater force on tissue.21 Based upon the published medical literature, although only a small percentage of cryolipolysis procedures resulted in PAH, 
