Langerhans Cell Histiocytosis

Histiocytoses are rare disorders characterized by the pathological proliferation of monocyte and macrophage lineages, of which Langerhans’ cell histiocytosis (LCH) is the most common [1, 2]. Historically, the classification and naming of histiocytic disorders, including LCH, has been challenging due to the variety of clinical presentations which are a function of which organ system(s) have been invaded by the pathological cells. Presentation ranges from a self-limiting skin rash to fulminant multisystem disease with high mortality [3]. Previously described eponyms associated with particular presentations of LCH, such as eosinophilic granuloma, Hand-Schüller-Christian, and Letterer-Siwe disease, are of historical interest but should be disregarded in clinical practice [4]. In 1987, the Writing Group of the Histiocytosis Society proposed that Histiocytosis X be reclassified as LCH, the currently accepted term [5].