Post-Inflammatory Hyperpigmentation
Post-inflammatory hyperpigmentation (PIH) is temporary darkening of the skin at a site that has been inflamed or injured. Inflammation stimulates melanocytes to make more melanin and pass it to the surrounding skin cells (epidermal melanosis). Scratching and rubbing can also release pigment into the deeper dermis, where it is trapped and gives a grey-brown hue that fades more slowly (DermNet 2015; National Eczema Society). In a toddler with Atopic Dermatitis, PIH appears as brown to dark patches exactly where flares, scratch marks or Lichenification have been. It occurs in all skin types but is more intense and lasts longer on brown and black skin (DermNet). It is one of the main reasons eczema looks different in skin of colour, where redness may be hard to see and darkening or greyness is the visible sign of active disease (NES).
Atopic Dermatitis [causes] Post-Inflammatory Hyperpigmentation Itch-Scratch Cycle [worsens] Post-Inflammatory Hyperpigmentation Post-Inflammatory Hyperpigmentation [relates] Eczema in Skin of Colour
Why it matters for parents. The dark marks can linger for months after the eczema has settled, even if it never returns to that spot (NES). Parents may read lingering darkness as ongoing eczema and keep applying steroid, or may blame the treatment. The NES advises against continuing Topical Corticosteroids on areas that are only discoloured, because long-term use there risks permanent hypopigmentation. The key test is whether the skin is still itchy, rough or raised (active eczema) or flat and smooth (PIH). PIH also follows other rashes common in toddlers, including Irritant Contact Dermatitis, Lip-Licker’s Dermatitis and Nappy Rash (DermNet).
Irritant Contact Dermatitis [causes] Post-Inflammatory Hyperpigmentation Lip-Licker’s Dermatitis [causes] Post-Inflammatory Hyperpigmentation
Prevention and treatment. The best prevention is prompt, adequate treatment of flares so that inflammation and scratching are short-lived (NES). Sunlight darkens PIH, so sun protection (shade, clothing and a suitable sunscreen on exposed skin) helps it fade and prevents more darkening (NES; DermNet). The patches fade gradually on their own. DermNet lists bleaching and resurfacing treatments such as hydroquinone, retinoids, peels and lasers, but these are adult options and are not appropriate for toddlers. Physical treatments can also worsen pigmentation by injuring the skin.
Post-Inflammatory Hyperpigmentation [relates] Topical Corticosteroids
Connections
- Eczema in Skin of Colour — lasting dark marks after flares, source: NES
- Atopic Dermatitis — inflammation and scratching cause PIH, source: NES; DermNet 2015
- Lichenification — chronically rubbed skin is always hyperpigmented, source: NES
- Irritant Contact Dermatitis — PIH common after resolution in darker skin, source: DermNet ICD
- Pityriasis Alba — contrasting pale (hypopigmented) change, source: NES
- Topical Corticosteroids — do not continue on discoloured-only skin, source: NES