Pityriasis lichenoides has an acute and chronic phase. The acute form is called Pityriasis lichenoides et varioliformis acuta (PLEVA) or Mucha-Habermann disease. Pityriasis lichenoides is a rare skin disorder that will not harm your general health. It is a disease of the immune system. It is possible that once the rash flattens out a brown mark will be left on the individual’s skin. These brown marks do begin to fade after several months. Pityriasis Lichenoides can affect all individuals equally. It does seem to affect more males than females. It rarely affects infants and individuals of old age.
Pityriasis lichenoides encompasses a spectrum of clinical presentations ranging from acute papular lesions that rapidly evolve into pseudovesicles and central necrosis (pityriasis lichenoides et varioliformis acuta or PLEVA) to small, scaling, benign-appearing papules (pityriasis lichenoides chronica or PLC).
The common causes and risk factors of Pityriasis lichenoides include the following:
- The exect cause of pityriasis lichenoides is not known.
- The symptoms which appear in the childhood suggest that it might follow a virus infection.
- The reaction of over-sensitiveness to the infectious agents is the principal cause of this disease.
- The infections of toxoplasme are asymptomatic, and the toxoplasmose can also be a cause.
- Parvovirus B19 and adenovirus can also trigger Mucha-Habermann disease.
- It is considered as a non-contagious disease that is not spread by touch.
There may be a mild illness with a fever. The rash starts as separate pink spots, which form a little blister and may turn black. A crust forms on the surface and drops off to leave a small scar. The lesions are small firm red-brown spots, 3 to 18 mm in diameter. In PLC they are non-irritating and have mica-like adherent scale, which can be scraped off to reveal a shiny brown surface. The spot flattens out over several weeks to leave a brown mark which fades over several months.
Very little trial data exists for the use of drugs in pityriasis lichenoides, although many agents have been tried including several antibiotics, dapsone, methotrexate, chloroquine and pentoxifylline. Erythromycin and tetracycline are used most frequently although there is little trial data to support their use. Reports suggest that antibiotics given for one month help some patients. Natural sunlight may be effective, and treatment with special ultraviolet light lamps (not ordinary sun beds) can also help.