Post-inflammatory Pigmentation

Postinflammatory pigmentation is temporary pigmentation that follows injury (eg, a thermal burn) or inflammatory disorder of the skin (eg, dermatitis, infection). It is mostly observed in darker skin types (see ethnic dermatology). Postinflammatory pigmentation is also called acquired melanosis.

More severe injury results in postinflammatory hypopigmentation, which is usually permanent.

Postinflammatory hyperpigmentation follows damage to the epidermis and/or dermis with deposition of melanin within the keratinocytes (skin cells) and/or dermis.

Inflammation in the epidermis stimulates melanocytes to increase melanin synthesis and to transfer the pigment to surrounding keratinocytes (epidermal melanosis). If the basal layer is injured (e.g. lichen planus), melanin pigment is released and subsequently trapped by macrophages in the papillary dermis (dermal melanosis or pigment incontinence).