What is postinflammatory hyperpigmentation?
Postinflammatory hyperpigmentation is a discolouration that is left on the skin after an underlying skin disease has healed. These underlying conditions include:
- skin infections
- allergic reactions
- mechanical injuries
- reactions to medications
- phototoxic eruptions
- trauma (e.g. burns)
- inflammatory reactions (e.g. acne, dermatitis, lichen planus).
Lichen planus actinicus
Violin playing (friction)
The postinflammatory hyperpigmented lesions are located at the site of the originating disease after it has healed. The lesions range from light brown to black in colour. Lesions may become darker if exposed to sunlight (UV rays). Some medications may also darken lesions and include antimalarial drugs, clofazimine, tetracycline, anticancer drugs such as bleomycin (flagellate erythema), doxorubicin, 5-fluorouracil and busulfan.
Postinflammatory hyperpigmentation can occur in anyone, but is more common in darker skinned individuals, in whom the colour tends to be more intense and persists for a longer period. The condition is also more apparent in sun-induced skin conditions such as phytophotodermatitis and more severe in lichenoid dermatoses (skin conditions related to lichen planus).
What is the cause of postinflammatory hyperpigmentation?
Inflammatory responses of the epidermal skin layer to disease or trauma results in the release and oxidation of arachidonic acid to prostaglandins, leukotrienes and other products. These products alter the activity of immune cells and melanocytes. Melanocytes produce more melanin (skin colour pigment), which is transferred to surrounding keratinocytes (skin cells). This is known as epidermal hypermelanosis.
Another cause is dermal hypermelanosis, a deeper pigmentation that occurs when inflammation disrupts the basal cell layer (the bottom of the epidermis), causing melanin pigment to be released into the papillary dermis (the top part of the dermis). The pigment may be trapped by large immune cells called tissue macrophages.
What is the treatment for postinflammatory hyperpigmentation?
Usually, hyperpigmentation will gradually lessen over time and normal skin colour will return. However, this is a long process that may take up to 6-12 months or longer. Patients should be advised to use a good broad spectrum sunscreen daily to reduce further darkening.
A variety of topical treatments are available to lighten/bleach hyperpigmented lesions in epidermal hypermelanosis. Varying degrees of success are achieved but combinations of the treatments below are usually required for significant improvement.
These treatments are not effective in dermal hypermelanosis.
Cosmetic camouflage techniques using pigmented makeup can also be used to camouflage hyperpigmented skin to a hue that is similar to surrounding unaffected skin.
- Book: Textbook of Dermatology. Ed Rook A, Wilkinson DS, Ebling FJB, Champion RH, Burton JL. Fourth edition. Blackwell Scientific Publications.
On DermNet NZ:
- Postinflammatory Hyperpigmentation – Medscape Reference
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See the DermNet NZ bookstore