title: Progressive hemifacial atrophy: a review.
abstract: BACKGROUND
  Progressive Hemifacial Atrophy (PHA) is an acquired, typically unilateral, facial distortion with unknown etiology. The true incidence of this disorder has not been reported, but it is often regarded as a subtype of localized scleroderma. Historically, a debate existed whether PHA is a form of linear scleroderma, called morphea en coup de sabre (ECDS), or whether these conditions are inherently different processes or appear on a spectrum (; Adv Exp Med Biol 455:101-4, 1999; J Eur Acad Dermatol Venereol 19:403-4, 2005). Currently, it is generally accepted that both diseases exist on a spectrum of localized scleroderma and often coexist. The pathogenesis of PHA has not been delineated, but trauma, autoimmunity, infection, and autonomic dysregulation have all been suggested. The majority of patients have initial manifestations in the first two decades of life; however, late presentations in 6th and 7th decades are also described [J Am Acad Dermatol 56:257-63, 2007; J Postgrad Med 51:135-6, 2005; Neurology 61:674-6, 2003]. The typical course of PHA is slow progression over 2-20 years and eventually reaching quiescence. Systemic associations of PHA are protean, but neurological manifestations of seizures and headaches are common [J Am Acad Dermatol 56:257-63, 2007; Neurology 48:1013-8, 1997; Semin Arthritis Rheum 43:335-47, 2013]. As in many rare diseases, standard guidelines for imaging, treatment, and follow-up are not defined.
  
  
  METHODS
  This review is based on a literature search using PubMed including original articles, reviews, cases and clinical guidelines. The search terms were "idiopathic hemifacial atrophy", "Parry-Romberg syndrome", "Romberg's syndrome", "progressive hemifacial atrophy", "progressive facial hemiatrophy", "juvenile localized scleroderma", "linear scleroderma", and "morphea en coup de sabre". The goal of this review is to summarize clinical findings, theories of pathogenesis, diagnosis, clinical course, and proposed treatments of progressive hemifacial atrophy using a detailed review of literature.
  
  
  METHODS
  Review articles were used to identify primary papers of interest while retrospective cohort studies, case series, case reports, and treatment analyses in the English language literature or available translations of international literature were included.
authors.affiliation: Mayo Clinic, Department of Dermatology, 200 First Street SW, Rochester, MN, 55905, USA. Tolkachjov.stanislav@mayo.edu.
authors.forename: Stanislav N
authors.initials: SN
authors.lastname: Tolkachjov
authors.affiliation: Mayo Clinic, 13400 E. Shea Blvd, Scottsdale, AZ, 85259, USA. patel.nirav@mayo.edu.
authors.forename: Nirav G
authors.initials: NG
authors.lastname: Patel
authors.affiliation: Mayo Clinic, Department of Dermatology, 200 First Street SW, Rochester, MN, 55905, USA. Tollefson.Megha@mayo.edu.
authors.forename: Megha M
authors.initials: MM
authors.lastname: Tollefson
mesh_terms: D005150:Facial Hemiatrophy / Q000473:pathology*; D006801:Humans; D012594:Scleroderma, Localized