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POSTINFLAMMATORY HYPERPIGMENTATION
POSTINFLAMMATORY HYPERPIGMENTATION
Postinflammatory hyperpigmentation (PIH) is an acquired dyschromia that usually occurs after either acute or chronic skin inflammation or injury. PIH can arise in all skin types, but more frequently affects patients with darker skin (Fitzpatrick skin types IVโ VI).7
Etiology
Various types of inflammatory conditions or cutaneous injuries lead to pigmentary changes including both hyper- and hypopigmentation. However, certain diseases show a greater tendency toward development of hyperpigmentation such as dermatophytoses, viral exanthems, insect bite reaction, contact dermatitis, lichen planus, drug hypersensitivity reactions, and acne vulgaris.8
Pathogenesis
The excess production of melanin as a result of inflammation leads to epidermal PIH. An irregular dispersion of pigment as the result of an inflammatory process causes dermal PIH. Inflammation damages basal keratinocytes, leading to release of melanin into the dermis followed by phagocytosis and formation of melanophages in the upper dermis. The rise in melanocyte activity is stimulated by inflammatory mediators such as prostacyclins, cytokines, and chemokines as well as ROS released during the inflammatory process.7