title: The association between melasma and postinﬂammatory hyperpigmentation in acne patients.
abstract: BACKGROUND
  Although, melasma is most prevalent among Asian young women, and also darkly pigmented individuals are particularly prone to developing post inflammatory hyperpigmentation, to the best of our knowledge, there are rare or no studies about the association of melasma and Post inflammatory hyperpigmentation.
  
  
  OBJECTIVE
  The aim of this study was to investigate how likely is a melasma patient to developed post inflammatory hyperpigmentation when compared to patients with inflammatory acne lesions who do not have melasma.
  
  
  METHODS
  This comparative study was conducted on 400 participants, 200 subjects involved with pigmented lesions of melasma and inflammatory acne lesions and200 involved only with inflammatory Acne lesions without melasma. Melasma, acne and post inflammatory hyper pigmentation, if existed, were assessed by a dermatologist, and pigmentation depth was assessed by wood's lamp. Multivariate logistic regression analysis suitable for study design was used to assess the association between melasma and post-acne pigmentation.
  
  
  RESULTS
  We found out that 24.1% of patients without melasma had post-acne pigmentation compared to 66.8% in melasma group (P < 0.001). The likelihood of observing post-acne pigmentation was found to be nearly six times more in melasma patients versus those without melasma. Association existed after controlling for possible confounders such as melanin score and time length of self-reported sun exposure, and acne severity score.
  
  
  CONCLUSIONS
  Melasma appears to increase the likelihood of post-acne pigmentation.
authors.affiliation: Department of Dermatology, Ardabil University of medical sciences, Ardabil, IR Iran.
authors.forename: Hassan
authors.initials: H
authors.lastname: Adalatkhah
authors.affiliation: Department of Statistics and Epidemiology, Tabriz University of medical sciences, Tabriz, IR Iran.
authors.forename: Homayoun
authors.initials: H
authors.lastname: Sadeghi Bazargani
keywords: Acne Vulgaris; Hyperpigmentation; Melanosis