Pityriasis Lichenoides et Varioliformis Acuta (PLEVA) is also known as Mucha-Habermann disease. The eruption often appears suddenly in children and young adults. At onset the lesions are erythematous macules, papules or papulovesicles, which tend to be brownish red in color, ranging from 5-15 mm in size and evolve through stages of crusting, necrosis and varioliform scarring. The lesions tend to occur in crops numbering from just a few to hundreds. The name is due to the misconception that this is actually chicken pox, which can look very similar. The lesions occur most commonly on the trunk but may be found to involve even the palms and soles. Dermoscopy may be useful, demonstrating red thin papules with dark and light brown dots distributed within and outside of the lesion.
The patients usually feel well and the natural history of the disease is benign but it may take 1-3 years for the lesions to resolve, or involute. A subset of PLEVA is ulceronecrotic Mucha-Habermann disease, in which black necrotic papules rapidly develop into large crusted ulcerations, blood-filled blisters and pustules. This form of PLEVA is often very painful and the ulcers may become infected. Associated symptoms may include high fever, sore throat, diarrhea, abdominal pain, central nervous system symptoms, lung disease, enlarged spleen, arthritis, sepsis, anemia and conjunctival ulcers.
HISTOLOGY: On histology the biopsy is often characterized by epidermal necrosis together with hemorrhage and a dense perivascular infiltrate within the upper and middle dermis–often having a wedge-shaped pattern. A lymphocytic vasculitis may be observed. T-cell gene rearrangements may be found, but interpretation of the significance of this finding remains obscure.
TREATMENT: The most common form of treatment is either erythromycin or tetracyclines. Phototherapy may be useful (broad- or narrow-band UVB, PUVA, or PDT). Topical agents that may be helpful include tacrolimus and/or topical steroids. In severe cases low-dose methotrexate may be required. A rapid response to the use of azithromycin has been reported but not verified. Although etanercept has been reported effective, another TNF-inhibitor, infliximab, has been shown to actually cause PLEVA. To read more about PLEVA click HERE, HERE and HERE.