Acquired cutaneous Langerhans cell histiocytosis.

Skin lesions worsen the prognosis of Langerhans cell histiocytosis when they are added to lesions of other organs, indicating a generalization of the disease.When the lesions affect only the skin, the prognosis of the disease is generally better, especially when there is a single lesion and when the skin lesions are present at birth: in these cases there is a spontaneous regression of the disease in most cases (1).When the skin lesions are acquired in the first months of life the disease can regress spontaneously; however, it can also progress towards multisystem involvement. Therefore, prolonged dermatological and onco-hematological monitoring is required in the acquired skin form (2). In the present case the exclusive skin involvement, the scarcity of lesions and the lack of purpuric lesions were expression of a favorable prognosis.