title: Depigmented genital extramammary Paget's disease: a possible histogenetic link to Toker's clear cells and clear cell papulosis.
abstract: BACKGROUND
  The histogenesis of extramammary Paget's disease (EMPD) is still controversial. Benign pagetoid cells of the nipple first described by Toker and the similar clear cells found in white maculopapules of clear cell papulosis (CCP) have been proposed to be potential precursor cells giving rise to EMPD and primary intraepidermal Paget's disease in the nipple. The observation of a rare case of depigmented EMPD provided us with a chance to examine further the interesting Toker's clear cell/CCP hypothesis.
  
  
  METHODS
  We performed pathologic studies, including Fontana-Masson stain and immunostaining for AE1/AE3 and S100P, on a new case of depigmented EMPD manifesting a 4 x 3 cm hypopigmented-depigmented patch on the root of the penis.
  
  
  RESULTS
  The lesion showed extensive intraepithelial proliferation of atypical pagetoid cells with markedly reduced epidermal melaninization but nearly normal numbers of melanocytes. The tumor cells were strongly positive for AE1/AE3 by immunostaining. Some tumor cells displayed tadpole-like morphology resembling the pagetoid cells of CCP. Such morphology was not observed in two random examples of non-depigmented genital EMPD.
  
  
  CONCLUSIONS
  The findings of tadpole-shaped pagetoid cells and depigmentation in the present case suggest that depigmented EMPD may be histogenetically related to CCP. Depigmented EMPD should be considered in the differential diagnosis of vitiligo, depigmented mycosis fungoides and lichen sclerosus located along the milk line.
authors.affiliation: Department of Dermatology, National Cheng-Kung University Hospital, Tainan, Taiwan.
authors.forename: Y H
authors.initials: YH
authors.lastname: Chen
authors.forename: T W
authors.initials: TW
authors.lastname: Wong
authors.forename: J Y
authors.initials: JY
authors.lastname: Lee
mesh_terms: D000368:Aged; D027321:Anion Transport Proteins; D017920:Antiporters / Q000032:analysis; D027963:Chloride-Bicarbonate Antiporters; D003937:Diagnosis, Differential; D006801:Humans; D006965:Hyperplasia / Q000473:pathology; D017496:Hypopigmentation / Q000150:complications / Q000473:pathology*; D007150:Immunohistochemistry; D018459:Lichen Sclerosus et Atrophicus / Q000175:diagnosis; D008297:Male; D008565:Membrane Proteins / Q000032:analysis; D009182:Mycosis Fungoides / Q000175:diagnosis; D010145:Paget Disease, Extramammary / Q000737:chemistry / Q000209:etiology / Q000473:pathology*; D010413:Penis / Q000473:pathology; D064606:SLC4A Proteins; D012867:Skin / Q000473:pathology*; D017444:Skin Diseases, Papulosquamous / Q000150:complications / Q000473:pathology*; D012878:Skin Neoplasms / Q000737:chemistry / Q000209:etiology / Q000473:pathology*; D014820:Vitiligo / Q000175:diagnosis
chemical_list: D027321:Anion Transport Proteins; D017920:Antiporters; D027963:Chloride-Bicarbonate Antiporters; D008565:Membrane Proteins; D064606:SLC4A Proteins