Histopathological comparison of lesional and perilesional skin in melasma: A cross-sectional analysis

Melasma is a common acquired hyperpigmentary disorder of the sun exposed skin, especially the face. The pathogenesis is unclear but interplay between genetic factors, hormones and ultraviolet radiation is important. We have evaluated the histological characteristics of melasma and compared the findings with adjacent normal skin.

Skin biopsies were taken from both melasma and the surrounding perilesional normal skin in 50 Indian women. The sections were stained with hematoxylin and eosin, Fontana-Masson and Verhoeff-Van Gieson stains.

Biopsy from melasma showed significant epidermal atrophy, basal cell hyperpigmentation and solar elastosis when compared with the perilesional skin. We found that the proportion of pendulous melanocytes was significantly higher in the lesional biopsy compared with the perilesional biopsy (76% vs 42%, P < 0.001). Similarly, pigmentary incontinence and features of solar elastosis were significantly higher in the lesional skin compared with the perilesional skin.

The characteristic histopathological features such as epidermal atrophy, basal cell hyperpigmentation and solar elastosis suggest the role of chronic sun exposure in the pathogenesis of melasma. Presence of pendulous melanocytes is a characteristic feature of melasma. The presence of pendulous melanocytes may have prognostic implications in melasma.