Langerhans cell histiocytosis (LCH) is a rare disorder characterized by an abnormal clonal proliferation of immature immune system cells called langerhans cells. It was presumed that epidermal langerhans cells are the cells of origin in LCH but recent studies have found many other cells that possess phenotypic characteristics similar to langerhans cells like dermal langerin dendritic cells, lymphoid tissue resident langerin dendritic cells, and monocytes induced by local environmental stimuli (Allen et al., N Engl J Med. 379:856–868, 2018) This disorder represents a clonal expansion of CD1a and CD207-positive myeloid-committed hematopoietic progenitors in the bone marrow compartment (Picarsic and Jaffe, Hematol Oncol Clin North Am. 29:799–823, 2015) LCH is considered to be an uncommon disease, occurring only in up to 8.9 per million children under the age of 15 with a median age of 3 years when diagnosed. LCH is even less common in adults, occurring in only approximately 0.07 per million annually (Rodriguez-Galindo and Allen, Blood. 135:1319–1331, 2020) Langerhans cell histiocytosis can affect only one system or may present as a multisystem disease. It frequently affects the skin and bones but can also affect bone marrow, lymph nodes, and viscera, including the lungs, brain, liver, and spleen. From a clinical standpoint, the management of LCH necessitates a multidisciplinary approach involving pediatricians, oncologists, radiologists, pathologists, and, in some cases, neurologists and pulmonologists (Emile et al., Blood. 127:2672–81, 2016) Long-term follow-up is essential due to the risk of relapse and development of permanent sequelae such as diabetes insipidus, growth failure, neurodegeneration, and skeletal deformities (Rodriguez-Galindo and Allen, Blood. 135:1319–1331, 2020; McClain et al. Cancer 124(12):2607–2620, 2018). The overall prognosis is variable and heavily dependent on the extent of disease at presentation, organ involvement (particularly “risk organs” such as the liver, spleen, and bone marrow), and the early response to initial therapy (Rodriguez-Galindo and Allen, Blood. 135:1319–1331, 2020). Amid the various treatment options available ranging from observation to chemotherapy, surgery, photodynamic therapy, immunotherapy, stem cell transplant, etc. radiation therapy has also maintained its existence. In recent years, the landscape of LCH has shifted from empiric treatment based on histologic findings to a more sophisticated, mutation-driven therapeutic strategy (Berres et al. J Exp Med 211(4):669–683, 2014; Chakraborty et al. Blood. 124(19):3007–3015, 2014).

Langerhans Cell Histiocytosis

章节
发表日期：

2026年

查看全文

Aditi Tanwar,
Pankaj Gupta,
Mimansha Patel

摘要

Langerhans cell histiocytosis (LCH) is a rare disorder characterized by an abnormal clonal proliferation of immature immune system cells called langerhans cells. It was presumed that epidermal langerhans cells are the cells of origin in LCH but recent studies have found many other cells that possess phenotypic characteristics similar to langerhans cells like dermal langerin dendritic cells, lymphoid tissue resident langerin dendritic cells, and monocytes induced by local environmental stimuli (Allen et al., N Engl J Med. 379:856–868, 2018) This disorder represents a clonal expansion of CD1a and CD207-positive myeloid-committed hematopoietic progenitors in the bone marrow compartment (Picarsic and Jaffe, Hematol Oncol Clin North Am. 29:799–823, 2015) LCH is considered to be an uncommon disease, occurring only in up to 8.9 per million children under the age of 15 with a median age of 3 years when diagnosed. LCH is even less common in adults, occurring in only approximately 0.07 per million annually (Rodriguez-Galindo and Allen, Blood. 135:1319–1331, 2020) Langerhans cell histiocytosis can affect only one system or may present as a multisystem disease. It frequently affects the skin and bones but can also affect bone marrow, lymph nodes, and viscera, including the lungs, brain, liver, and spleen. From a clinical standpoint, the management of LCH necessitates a multidisciplinary approach involving pediatricians, oncologists, radiologists, pathologists, and, in some cases, neurologists and pulmonologists (Emile et al., Blood. 127:2672–81, 2016) Long-term follow-up is essential due to the risk of relapse and development of permanent sequelae such as diabetes insipidus, growth failure, neurodegeneration, and skeletal deformities (Rodriguez-Galindo and Allen, Blood. 135:1319–1331, 2020; McClain et al. Cancer 124(12):2607–2620, 2018). The overall prognosis is variable and heavily dependent on the extent of disease at presentation, organ involvement (particularly “risk organs” such as the liver, spleen, and bone marrow), and the early response to initial therapy (Rodriguez-Galindo and Allen, Blood. 135:1319–1331, 2020). Amid the various treatment options available ranging from observation to chemotherapy, surgery, photodynamic therapy, immunotherapy, stem cell transplant, etc. radiation therapy has also maintained its existence. In recent years, the landscape of LCH has shifted from empiric treatment based on histologic findings to a more sophisticated, mutation-driven therapeutic strategy (Berres et al. J Exp Med 211(4):669–683, 2014; Chakraborty et al. Blood. 124(19):3007–3015, 2014).