Melasma pathogenesis: a review of the latest research, pathological findings, and investigational therapies.

Melasma is an acquired hyperpigmentation disorder most commonly affecting females with darker skin types. It is triggered by several factors including sun exposure, genetic influences, and female sex hormones. The pathology of melasma extends beyond melanocytes and recent literature points to interactions between keratinocytes, mast cells, gene regulation abnormalities, neovascularization, and disruption of basement membrane. This complex pathogenesis makes melasma difficult to target and likely to recur post treatment. A better understanding of the latest pathological findings is key to developing novel and successful treatment options. This review aims to provide a summary of the more novel pathological findings and latest investigational therapies.