Histiocytosis in the dermatological context of the new classification

Abstract

Histiocytoses comprises a heterogeneous group of inflammatory diseases for which dendritic cells and macrophages are the main cellular components. The inflammatory infiltrate can affect the skin and other organs, and clinical outcome varies from mild to lethal depending on the involved cell subset and organ infiltration as well as comorbidities. Until recently, the group of histiocytosis was divided into Langerhans cell histiocytosis, non-Langerhans cell histiocytosis and malignant histiocytosis. With the new classification from JF Emile et al., the subgroups were determined regarding clinical, histiopathological, radiological, phenotype, genetic, and molecular features. In this review, we explain the revised classification with emphasis on dermatological and molecular aspects.