Changes in nuclear morphology and chromatin texture of basal keratinocytes in melasma.

BACKGROUND: The pathogenesis of melasma and the role of keratinocytes in disease development and maintenance are not completely understood. Dermal abnormalities, the expression of inflammatory mediators, growth factors, epithelial expression of melanocortin and sexual hormones receptors suggest that not only melanocytes, but entire epidermal melanin unit is involved in melasma physiopathology. OBJECTIVES: To compare nuclear morphological features and chromatin texture between basal keratinocytes in facial melasma and adjacent normal skin. METHODS: We took facial skin biopsies (2 mm melasma and adjacent normal skin) from women processed for haematoxylin and eosin. Thirty non-overlapping basal keratinocyte nuclei were segmented and descriptors of area, highest diameter, perimeter, circularity, pixel intensity, profilometric index (Ra) and fractal dimension were extracted using ImageJ software. RESULTS: Basal keratinocyte nuclei from facial melasma epidermis displayed larger size, irregular shape, hyperpigmentation and chromatin heterogeneity by fractal dimension than perilesional skin. CONCLUSION: Basal keratinocytes from facial melasma display changes in nuclear form and chromatin texture, suggesting that the phenotype differences between melasma and adjacent facial skin can result from complete epidermal melanin unit alterations, not just hypertrophic melanocytes.

Risk factors for facial melasma in women: a case-control study.

BACKGROUND: Melasma is a localized chronic acquired hypermelanosis, common in adult women and which has an important impact on their life quality. Its pathology is unknown, despite some recognized triggering factors. OBJECTIVE: To evaluate risk factors for developing facial melasma in women. METHODS: This was a case-control study involving adult women with or without facial melasma, paired by age. Variables were grouped into hierarchical levels: personal characteristic data, exposure variables, links to hormonal stimuli and the State-Trait Anxiety Inventory questionnaire, Brazilian version. The data were analysed using conditional multiple logistic regression. RESULTS: We evaluated 207 patients and 207 controls. The mean age was 38 years. Cases differed from controls for phototype, Amerindian ancestry [odds ratio (OR) 2·59], years of beach or rural residence (OR 1·06), time exposed to sun at work (OR 1·65), time exposed to sun in leisure activities (OR 1·04), antidepressant/anxiolytic use (OR 4·96), menstrual irregularity (OR 3·83), pregnancy history (OR 3·59), years of oral contraceptive use (OR 1·23) and anxiety scores (OR 1·08). A family history of melasma was reported in 61% of cases and 13% of controls (OR 10·40). CONCLUSIONS: Facial melasma is independently associated with elements linked to pigmentation capacity, family ancestry, chronic sun exposure, sexual hormone stimuli, psychotropics and anxiety traits.