What is mucha-habermann disease? how common is it?

Mucha habermann: Mucha habermann disease is a rare skin disorder. It is also known as pityriasis lichenoides et varioliformis acuta or PLEVA. Lesions can sometimes itch, - tend to be found in groups on trunk, arms and legs. PLEVA can disappear in 1.5 to 18 months without treatment. Scarring can occur. PLEVA is most often seen in children and young adults.