Pityriasis lichenoides chronica

Pityriasis lichenoides chronica (PLC) is an uncommon, idiopathic, acquired dermatosis, characterized by evolving groups of erythematous, scaly papules that may persist for months. 
Symptoms and signs.
Although other forms of the disease occur at younger ages, some individuals start having long term symptoms at thirty years of age. This disease also affects adolescents and young adults. This also affects the immune system which therefore results in rashes. The symptoms rarely affect the face or scalp, but occurs at other sites of the body. The duration may last for months or even several years. For instance, new crops of lesions appear every few weeks.
Causes.
Pityriasis lichenoides chronica is probably caused by a hypersensitivity reaction to infectious agents such as the Epstein–Barr virus. Other infectious agents include the adenovirus and Parvovirus B19.
Treatment.
There is no standard treatment for PLC. Treatments may include ultraviolet phototherapy, topical steroids, sun exposure, oral antibiotics, corticosteroid creams and ointments to treat rash and itching.One study identified the enzyme bromelain as an effective therapeutic option for PLC.