What is pityriasis lichenoides?
Pityriasis lichenoides is a rare skin disorder of unknown cause. There are two types of pityriasis lichenoides: an acute form usually found in children known as pityriasis lichenoides et varioliformis acuta (PLEVA) and a more longlasting form known as pityriasis lichenoides chronica (PLC).
What causes pityriasis lichenoides?
The cause of pityriasis lichenoides is not known. The symptoms that occur in the childhood form suggest it is a reaction to a bacterial infection or a viral infection. It is more common in males than in females. Neither type of pityriasis lichenoides is infectious.
Is it hereditary?
No.
What are the symptoms of pityriasis lichenoides?
The main skin sign you may notice is raised small pink spots that tend to come together in groups. New areas can itch or irritate as they come up.
How does pityriasis lichenoides look like?
- The acute form (PLEVA): Initially, there may be a mild illness with a fever. The rash starts as small pink spots, forming a little blister and may turn a reddish-brown color. A crust forms on the surface and drops off to leave a small scar, which usually fades to some extent over several months. The spots come up in groups, and so the rash consists of spots at various stages of development. The rash can often be mistaken for chickenpox but takes much longer to clear than chickenpox. It rarely affects the face, but the spots are usually scattered on the trunk, arms, and legs.
- The chronic form (PLC): The spots look less angry and are covered with a firm, shiny scale (flake) of skin. This scale, which covers the top of a spot, can be scraped off to reveal a shiny, brownish surface underneath. Individual spots fade within 3 to 4 weeks, but new marks may then appear. The rash can clear up within a few weeks or persist for years.
How will it be diagnosed?
The appearance of the rash will suggest the diagnosis; however, PLEVA can often look like chickenpox but take much longer to clear, and PLC can look like psoriasis (red, flaky, crusty patch of skin covered with silvery scales). The examination under the microscope of a small sample of the rash (a skin biopsy) can confirm the diagnosis.
Can it be cured?
No treatment is sure to cure pityriasis lichenoides.
How can it be treated?
Reports suggest that antibiotics given for one month may help some patients. Natural sunlight may be helpful, and phototherapy treatment with UVB or UVA special ultraviolet light lamps (not ordinary sunbeds) can also help. A combination of tablets known as Psoralens with UVA (PUVA treatment) may also be helpful, but carries a higher risk of side effects. Immunosuppressants may manage severe forms of the disease.