What is Langerhans cell histiocytosis (LCH)?

Updated: Sep 16, 2020
  • Author: Cameron K Tebbi, MD; Chief Editor: Vikramjit S Kanwar, MBBS, MBA, MRCP(UK), FAAP  more...
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Histiocytoses encompass a group of diverse proliferative disorders characterized by the accumulation and infiltration of variable numbers of monocytes, macrophages, and dendritic cells in the affected tissues. Such a description excludes diseases in which infiltration of these cells occurs in response to a primary pathology. The clinical presentations vary greatly, ranging from mild to life threatening. While cases of histiocytosis were first described by Dr. Thomas Smith, in 1865, [1]  only in recent years, with the application of molecular analyses, has the pathophysiology of these disorders begun to be elucidated.

Over the last several decades, the nomenclature used to describe histiocytic disorders has substantially changed to reflect the wide range of clinical manifestations and the variable clinical severities of some disorders that have the same pathologic findings. [2] For example, the entity now referred to as Langerhans cell histiocytosis (LCH) was initially divided into eosinophilic granuloma, Hand-Schüller-Christian disease, and Abt-Letterer-Siwe disease, depending on the sites and severity. Later, these were found to be manifestations of a single entity and were unified under the term histiocytosis X. [3, 4]  This designation was changed to Langerhans cell histiocytosis based on the suggestion by Nezelof that the Langerhans cell represented the primary cell involved in the pathophysiology of the disease. [5, 6] Although several histiocytic disorders are briefly discussed in this article (see History), the primary focus is on Langerhans cell histiocytosis. [7, 8]

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