Melasma: Pathophysiology and Combination Therapy

Overview / Definition Melasma, also known as chloasma or "mask of pregnancy," is a common skin condition characterized by acquired hyperpigmentation. It typically presents as bilateral, irregularly shaped macules or patches of brown to gray-brown pigment, predominantly on the face, including the cheeks, forehead, nose, and chin. Epidemiology Melasma is more prevalent in women, especially those with darker skin types (Fitzpatrick skin types III-VI). The condition is particularly common in individuals aged 20 to 50 years, with a reported prevalence of: 10-15% in Caucasian populations 20-50% in Hispanic and Asian populations More than 50% in women with darker skin tones Pathophysiology / Mechanism The exact mechanism underlying melasma is multifactorial, involving genetic, hormonal, and environmental factors: Genetic predisposition: Family history is often noted in patients with melasma. Hormonal influences: Estrogen and progesterone are thought to play a significant role, particularly during pregnancy or with oral contraceptive use. UV exposure: Ultraviolet radiation stimulates melanocytes, leading to increased melanin production. Inflammation: Post-inflammatory hyperpigmentation may contribute to melasma in some cases. Clinical Presentation Clinically, melasma presents as: Symmetrical brownish macules or patches Commonly located on the face, especially the cheeks, forehead, and upper lip Asymptomatic, although some patients may experience mild itching or discomfort There are three clinical types of melasma based on the depth of pigmentation: Epidermal: Involves the upper layer of the skin, typically shows improvement with topical treatments. Dermal: Involves deeper skin layers, challenging to treat and often resistant to therapy. Mixed: A combination of both epidermal and dermal components. Diagnosis / Workup The diagnosis of melasma is primarily clinical, based on characteristic appearance and history. However, additional workup may include: Wood's lamp examination: