title: Prurigo pigmentosa: a clinicopathological study and analysis of associated factors.
abstract: BACKGROUND
  Prurigo pigmentosa (PP), a rare inflammatory disease of the skin, is mostly reported in the ethnic Japanese population. Its pathogenesis remains unclear. The chronic and recurrent nature of PP implies a possible role of viral infection in the pathogenesis. The anti-inflammatory mechanism of doxycycline, which is well documented as a good treatment for PP, is related to the suppression of interleukin expression.
  
  
  METHODS
  We identified and retrospectively analyzed 16 biopsy-proven and criteria-matched patients over a seven year period at a single medical center. DNA extracted from formalin-fixed, paraffin-embedded specimens was analyzed for herpes simplex virus-1 (HSV-1), HSV-2, and human herpes virus-6 (HHV-6) DNA by polymerase chain reaction. Immunohistochemistry was performed to determine the interleukin-6 (IL-6) and interleukin-8 (IL-8) expression in PP skin lesions.
  
  
  RESULTS
  Clinicopathological findings in the ethnic Chinese population are similar to those reported in Japanese studies. All patients had a good response to doxycycline treatment, with a mean duration of use of 2.4 weeks. However, recurrence was noted in six patients. HSV-1, HSV-2, and HHV-6 DNA in PP skin lesions were negative. Immunohistochemistry showed IL-6 (P = 0.035) to be more strongly expressed in PP skin lesions. There was no statistical significance of elevated IL-8 expression in PP (P = 0.123).
  
  
  CONCLUSIONS
  Prurigo pigmentosa is not uncommon in the ethnic Chinese population. There was no evidence of herpes virus DNA in PP skin lesions. Increased expression of IL-6 in PP skin lesions may explain the effects of doxycycline in terms of its anti-inflammatory properties.
authors.affiliation: Department of Dermatology, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taipei, Taiwan.
authors.forename: Pei-Hsuan
authors.initials: PH
authors.lastname: Lu
authors.forename: Rosaline C-Y
authors.initials: RC
authors.lastname: Hui
authors.forename: Li-Cheng
authors.initials: LC
authors.lastname: Yang
authors.forename: Chih-Hsun
authors.initials: CH
authors.lastname: Yang
authors.forename: Wen-Hung
authors.initials: WH
authors.lastname: Chung
mesh_terms: D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001706:Biopsy; D004318:Doxycycline / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D017495:Hyperpigmentation / Q000188:drug therapy / Q000821:virology; D007150:Immunohistochemistry; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011536:Prurigo / Q000188:drug therapy* / Q000473:pathology* / Q000821:virology; D012008:Recurrence; D012189:Retrospective Studies; D018139:Simplexvirus / Q000302:isolation & purification; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D015850:Interleukin-6; D016209:Interleukin-8; D004318:Doxycycline