title: Paradoxical adipose hyperplasia secondary to cryolipolysis: An underreported entity?
abstract: 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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Dermatology, The University of Texas Health Science Center at Houston, Houston, Texas.|Department of Dermatology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas.
authors.forename: Selina M
authors.initials: SM
authors.lastname: Singh
authors.affiliation: Dermatology and Laser Surgery Center, Houston, Texas.
authors.forename: Elizabeth R C
authors.initials: ER
authors.lastname: Geddes
authors.affiliation: Houston Plastic and Craniofacial Surgery Center, Houston, Texas.|Department of Plastic Surgery, The University of Texas Health Science Center at Houston, Houston, Texas.|Department of Plastic Surgery, Weill Cornell Medical College, Houston, Texas.
authors.forename: Sean G
authors.initials: SG
authors.lastname: Boutrous
authors.affiliation: Department of Plastic Surgery, Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Galiano
authors.affiliation: Department of Dermatology, The University of Texas Health Science Center at Houston, Houston, Texas.|Dermatology and Laser Surgery Center, Houston, Texas.|Department of Dermatology, Weill Cornell Medical College, New York, New York.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Friedman
mesh_terms: D000328:Adult; D017679:Cryotherapy / Q000009:adverse effects* / Q000379:methods; D006801:Humans; D006965:Hyperplasia / Q000209:etiology; D015187:Lipectomy / Q000009:adverse effects* / Q000379:methods; D008297:Male; D008875:Middle Aged; D050151:Subcutaneous Fat / Q000473:pathology* / Q000601:surgery
keywords: cryolipolysis; noninvasive body contouring