title: Extensive prurigo nodularis: characterization and etiology.
abstract: OBJECTIVE
  Prurigo nodularis (PN) has multiple reported disease associations, and this study analyzes the demographics, clinical distribution and underlying etiologies in an Asian cohort.
  
  
  METHODS
  A 1-year retrospective study was carried out on PN patients with extensive lesions (≥10) who attended a specialized itch clinic.
  
  
  RESULTS
  37 patients (46% male, median age 53 years) were included. In all patients, an underlying etiologic factor associated with pruritus could be identified. 49% (n = 18) of patients had a single attributable etiology, whilst 51% (n = 19) had multiple etiologies. Among all patients, dermatological disease was the most common cause (82%), of which endogenous eczema comprised the majority of cases (54%), followed by systemic disease (38%).
  
  
  CONCLUSIONS
  All patients with extensive PN had identifiable factors associated with pruritus in this study, and a dermatological condition was the predominant etiology in both patients with mono- and multifactorial disease. A significant number of patients had underlying systemic causes.
authors.affiliation: National Skin Centre, Singapore, Singapore.
authors.forename: Wei Sheng
authors.initials: WS
authors.lastname: Tan
authors.forename: Hong Liang
authors.initials: HL
authors.lastname: Tey
mesh_terms: D000328:Adult; D017677:Age Distribution; D017668:Age of Onset; D000368:Aged; D002908:Chronic Disease; D015331:Cohort Studies; D015897:Comorbidity; D004485:Eczema / Q000150:complications / Q000175:diagnosis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011379:Prognosis; D011536:Prurigo / Q000453:epidemiology* / Q000209:etiology / Q000473:pathology*; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D017678:Sex Distribution; D012846:Singapore