Histological Evaluation of Acquired Dermal Macular Hyperpigmentation

CONTEXT: An umbrella term, acquired dermal macular hyperpigmentation (ADMH), has been proposed to denote conditions including ashy dermatosis, erythema dyschromicum perstans, lichen planus pigmentosus, and idiopathic macular eruptive pigmentation. AIMS: To classify the patients manifesting ADMH on the basis of histology. SETTINGS AND DESIGN: In this retrospective, cross-sectional study, histology specimens of patients of ADMH, who underwent skin biopsy in our institution from 1.1 2015 to 31.12.2017, were included after obtaining ethical clearance. MATERIALS AND METHODS: The histology specimens of patients of ADMH were reviewed by the pathologist and classified. Clinical features of individual patient were collected from previous records and the data analyzed. STATISTICAL ANALYSIS USED: Pearson's Chi-square test was used to determine significance of association between age of onset and duration of pigmentation with histology type. RESULTS: Three patterns of histology were identified in the study group (17 males and 13 females). Type 1: Basal cell degeneration and moderate to dense inflammation (12 patients, 40%), type 2: Significant pigment incontinence and sparse inflammation without basal cell degeneration, (12 patients, 40%), and type 3: sparse inflammation without basal cell degeneration or significant pigment incontinence (six patients, 20%). Statistically significant association was noted between age of onset of pigmentation and histology type (P value, 0.02). LIMITATIONS: Main limitation was the small sample size. CONCLUSIONS: Prospective studies evaluating the clinical progression and dermoscopy features and analyzing serial biopsies of ADMH patients may confirm whether the histology patterns observed represent different stages of same disease process or are different entities.