title: Prurigo nodularis: systematic analysis of 58 histological criteria in 136 patients.
abstract: BACKGROUND
  To date, there has been no systematic investigation of the detailed histological features of prurigo nodularis (PN) in a large cohort of patients.
  
  
  METHODS
  This retrospective study includes skin biopsies of 136 patients (63 males, 73 females; mean age: 58.38 years) with PN.
  
  
  RESULTS
  Highly characteristic for PN is the presence of thick compact orthohyperkeratosis; the hairy palm sign (folliculosebaceous units in nonvolar skin in conjunction with a thick and compact cornified layer, like that of volar skin); irregular epidermal hyperplasia or pseudoepitheliomatous hyperplasia; focal parakeratosis; hypergranulosis; fibrosis of the papillary dermis with vertically arranged collagen fibers; increased number of fibroblasts and capillaries; a superficial, perivascular and/or interstitial inflammatory infiltrate of lymphocytes, macrophages and, to a lesser extent, eosinophils and neutrophils. For comparison, histological findings in 45 patients (18 males, 27 females; mean, 55.64 years) with lichen simplex (LS) were studied. PN and LS, both of them scratch-induced, had 50 of 58 (86.2%) histological features in common.
  
  
  CONCLUSIONS
  PN revealed a characteristic histological pattern. Absence of pseudoepitheliomatous hyperplasia or nerve fiber thickening, however, does not rule out the histological diagnosis of PN. A correlation of clinical and histological findings is necessary to reliably distinguish between PN and LS.
authors.affiliation: Department of Dermatology, Neurodermatology and Competence Center Pruritus, University of Münster, Münster, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Weigelt
authors.forename: Dieter
authors.initials: D
authors.lastname: Metze
authors.forename: Sonja
authors.initials: S
authors.lastname: Ständer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D002648:Child; D002908:Chronic Disease; D003937:Diagnosis, Differential; D004804:Eosinophils / Q000473:pathology; D005260:Female; D006801:Humans; D006965:Hyperplasia / Q000473:pathology; D007249:Inflammation / Q000473:pathology; D007642:Keratosis / Q000473:pathology; D008214:Lymphocytes / Q000473:pathology; D008264:Macrophages / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009450:Neurodermatitis / Q000473:pathology*; D011536:Prurigo / Q000473:pathology*; D012189:Retrospective Studies; D012867:Skin / Q000473:pathology*