Post-inflammatory hypopigmentation: pale patches after skin inflammation

Skin colour comes from pigment-producing cells. When the skin is inflamed or injured, pigment production in the affected area can be reduced, leaving lighter patches once the original problem settles. Patient.info's clinical reference describes the result as poorly defined whitening which is irregular in outline, usually with a surface that looks normal, or scaly if the underlying cause was a scaly condition such as eczema or psoriasis.

It is a consequence rather than a disease in its own right. The pale area marks where an earlier problem has been, such as an eczema flare, a burn, a rash or a treatment. It is not infectious and does not itself harm general health, although it can be distressing, particularly on visible areas and on darker skin where contrast is greater.

Patient.info says partial loss of pigment may follow any inflammatory skin reaction but is most noticeable in those with darker skin. Scarring conditions such as thermal burns, discoid lupus and lichen planus cause white atrophic hypopigmented areas. It also states that it is a recognised hazard of laser therapy.

The reference notes that the surface may be scaly if the cause is a scaly condition such as eczema or psoriasis, which is why pale marks often appear where a rash has been. A person who has had eczema or psoriasis plaques may notice pale patches in the same places after the rash clears.

• Eczema or psoriasis plaques that have settled.

• Burns or other injuries that have healed.

• Inflammatory conditions such as lichen planus or discoid lupus.

• Skin treatments including laser.

Patient.info lists the conditions that can look similar: vitiligo, which it says is normally well defined, geographic in shape and has complete loss of pigment; pityriasis versicolor, made of coalescing oval or round macules that may be slightly scaly; pityriasis alba, seen on the face of children as slightly scaly, poorly defined patches and common in children with dark skin; hypopigmented mycosis fungoides; naevus depigmentosus; nummular eczema; and idiopathic guttate hypomelanosis.

The NHS describes vitiligo as pale, white patches of skin, and notes that it may be triggered by events including skin damage such as severe sunburn or cuts. A history of earlier inflammation in the same place, and partial rather than total loss of colour, points towards post-inflammatory change rather than vitiligo. If there is doubt, a GP or dermatologist can examine the skin.

Patient.info says it may be possible to make the diagnosis on clinical grounds based on the appearance, size, site and distribution of lesions and the age and sex of the patient. A skin scraping for mycology or a biopsy for histopathology may be needed if there is doubt, and referral may be needed in cases of diagnostic difficulty.

Tell the clinician what the skin looked like before the pale patches appeared, and any treatments, creams or procedures used there.

Patient.info says treatment of the underlying condition is the mainstay of management, that with sun exposure the white areas should eventually repigment unless scarring has occurred, and that depigmentation often resolves spontaneously after weeks or months. A 308 nm excimer laser has been used to stimulate pigmentation in resistant cases, though regular treatment is needed to maintain results. Camouflage creams designed to last longer and give heavier masking than make-up are available, and are available on prescription although not all local authorities will allow them to be prescribed.

The NHS vitiligo advice stresses sun protection for pale areas because they are more vulnerable to sunburn, and using a sunscreen with a high sun protection factor. The same sensible approach protects patches of post-inflammatory change, which also have less pigment, although "sun exposure" in this context should be moderate and not deliberate sunbathing.

Most people with mild post-inflammatory change need only reassurance and treatment of the cause through their GP or a pharmacist. Referral to NHS dermatology is for diagnostic doubt or distressing, persistent change. Private dermatology and cosmetic clinics offer light-based treatments and camouflage, but it is worth confirming the diagnosis first so that the right condition is treated.