- Melasma is an acquired patchy hyperpigmentation largely due to increased melanin production, usually occurring in women and affecting the face.
- The precise etiology of melasma is unknown but sex hormones may be involved as it tends to occur in women during pregnancy or those taking OCPs. Historically melasma was also known as "Chloasma" or the "Mask of Pregnancy". Increased pigmentation is largely due to increased melanin production by melanocytes which only mildly proliferate.
- Melasma appears as irregularly-bordered but well-demarcated flat patches of hyperpigmentation, especially on the face. Increased melanin pigment is observed in the epidermal basal layer and melanocyte numbers may be mildly increased.
- Besides cosmesis melasma is not dangerous. Hyperpigmentation typically fades, over months to years, after delivery or discontinuation of OCPs.