An in vivo model for postinflammatory hyperpigmentation: an analysis of histological, spectroscopic, colorimetric and clinical traits

Br J Dermatol. 2016 Apr;174(4):862-8. doi: 10.1111/bjd.14184. Epub 2015 Dec 13.


Background: Acne vulgaris is a common condition that occurs in all skin types. Postinflammatory hyperpigmentation (PIH) is often associated with acne in patients of darker skin types, making it a common complaint in dermatology offices. Despite this, there is limited understanding of and effective treatment options for PIH.

Objectives: The study objective was to validate an in vivo model for PIH and to compare the clinical, histological and spectroscopic characteristics of artificially induced PIH and acne-induced PIH.

Methods: A nonblinded, nonrandomized pilot study was performed. Thirty subjects served as their own control in which four sites treated with 35% trichloroacetic acid (TCA) solution and four truncal acne pustules were followed for 8 weeks and were evaluated clinically and histologically, and by colorimetry and spectroscopy.

Results: The initial phases of inflammation between TCA- and acne-induced PIH differ. However, clinical evaluations were similar on and after day 14. Acne- and TCA-induced lesions were clinically, histologically and spectroscopically indistinguishable at day 28.

Conclusions: Clinical, spectroscopic and histological similarities of acne-induced and TCA-induced PIH at day 28 suggest that TCA-induced PIH can be a reproducible model for the study of acne-induced PIH.

Publication types

  • Comparative Study
  • Validation Study

MeSH terms

  • Acne Vulgaris / pathology*
  • Adolescent
  • Adult
  • Case-Control Studies
  • Caustics / toxicity
  • Colorimetry
  • Erythema / chemically induced
  • Erythema / pathology
  • Humans
  • Hyperpigmentation / chemically induced
  • Hyperpigmentation / pathology*
  • Middle Aged
  • Models, Biological*
  • Pilot Projects
  • Spectrum Analysis
  • Trichloroacetic Acid / toxicity
  • Young Adult


  • Caustics
  • Trichloroacetic Acid