RARE DISEASE
Langerhans cell histiocytosis
Langerhans cell histiocytosis
Langerhans cell histiocytosis
Synonyms: Histiocytosis X, Langerhans cell granulomatosis
Synonyms: Histiocytosis X, Langerhans cell granulomatosis
Synonyms: Histiocytosis X, Langerhans cell granulomatosis
Drug discovery
2
drugs
With orphan designations
Overview
Langerhans Cell Histiocytosis (LCH) is a rare neoplastic disorder characterized by clonal proliferation of dendritic cells with Langerhans-like features. Driven by MAPK/ERK pathway mutations (e.g., BRAF V600E), it manifests variably, ranging from localized bone/skin lesions to multisystem disease involving high-risk organs (liver, spleen, bone marrow). Diagnosis relies on biopsy (CD1a/CD207 positivity) and PET imaging. While low-risk cases often resolve with minimal intervention, high-risk disease requires systemic therapy. Targeted BRAF/MEK inhibitors show high efficacy, reducing reliance on chemotherapy [1][6][13][18].
Burden
Mortality: 5-year survival >95% in low-risk cases; high-risk organ involvement reduces survival to ~60–92% [12][17].
Morbidity: Neurodegeneration (2–5%), diabetes insipidus (25%), skeletal defects, and secondary cancers (16% in adults) [4][7][9].
Adults: Elevated non-LCH mortality (COPD, cardiovascular disease, malignancies) [7][11].
Therapies
Low-risk (single-system): Observation or local therapy (surgery/radiation) [1][17].
Multisystem: First-line vinblastine/prednisone; refractory cases use cladribine/cytarabine [3][12][16].
Targeted therapy: BRAF/MEK inhibitors (dabrafenib/trametinib) achieve 100% response in trials, reducing relapse risk [1][8][13].
Categories: rare hematological diseases, rare neoplastic diseases, rare respiratory diseases, rare systemic and rheumatological diseases, rare transplant-related disorders
Research Papers
1,279 drug discovery papers about Langerhans cell histiocytosis, with 2 first-in-class and 6 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
1,279 drug discovery papers about Langerhans cell histiocytosis, with 2 first-in-class and 6 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
2026-08-17 | Langerhans Cell Histiocytosis in Adults: A Canadian Multicenter Case Series.
Langerhans cell histiocytosis (LCH) is a rare clonal myeloid neoplasm. Canadian data on clinical characteristics, molecular profile, and treatment outcomes is limited. This study aims to report the initial experience of a Canadian rare diseases program, reflecting "real-world" diagnostic pathways, referral patterns, and treatment heterogeneity across multiple provinces. We conducted a retrospective review of patients managed in an adult-care cohort with histologically confirmed LCH diagnosed between 2000 and 2025 across multiple Canadian centers. Patients diagnosed as children and subsequently transferred to adult care were included. Clinical features, radiologic findings, histopathology, molecular testing, treatment approaches, and outcomes were collected and analyzed. Thirty-one patients were identified, with a median age at diagnosis of 42 years (range: 2-84) and a male predominance (65%). Bone (74%), lung (29%), and skin (16%) were the most commonly involved sites. Concomitant or subsequent malignancies were present in 19% of patients. Molecular testing found BRAFV600E mutations in 44% of tested patients. The most common first-line systemic therapy was cytarabine (n = 10), followed by other drugs such as hydroxyurea, vemurafenib, and cladribine. This series represents the initial experience of a Canadian rare disease referral program and captures the clinical heterogeneity and longitudinal adult care of patients with LCH across multiple provinces. Variability in treatment approaches highlights the need for collaborative prospective natural history studies and coordinated clinical trials.
2026-08-08 | Langerhans cell histiocytosis
Langerhans cell histiocytosis initially identified as an inflammatory disorder is now being referred as a rare dendritic/histiocytic neoplasm arising from dendritic cell differentiation with a heterogeneous clinical presentation manifesting in skin, bones, lungs, liver, lymph nodes, neurologic, and hematologic systems in any age group. Diagnostic work-up, staging investigations, prognostic markers, and therapeutic algorithms have seen a paradigm shift from pediatric-inspired chemotherapy regimens to a patient-tailored focused approach. Although chemotherapy is still the backbone in the era of novel circulating biomarkers and targeted agents in multisystem disease, chemoresistance and delayed neurological sequelae still remain challenges, resulting in dismal outcomes and poor quality of life.
2026-07-29 | Firm lesion consistency and whitish tissue exposure ingastrointestinal Langerhans cell histiocytosis
Keywords endoscopy upper GI tract - diagnosis and imaging (inc chromoendoscopy, NBI, iSCAN, FICE, CLE) - endoscopy lower GI tract - diagnosis and imaging (inc chromoendoscopy, NBI, iSCAN, FICE, CLE...) - Ulcers (peptic and other) Publication History Received: 25 May 2026 Accepted after revision: 15 July 2026 Article published online: 29 July 2026 © 2026. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/). Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany
2026-07-27 | Current Approaches Among Medical Providers Treating Pediatric Langerhans Cell Histiocytosis.
Most pediatric Langerhans cell histiocytosis (LCH) lesions harbor activating mutations within the mitogen-activated protein kinase (MAPK) pathway. MAPK inhibitors (MAPKi) represent a rational therapeutic strategy, though there is no consensus regarding optimal use. We sought to understand how providers currently integrate MAPKi into LCH therapy and gather input regarding potential future clinical trial designs. An online survey was distributed to members of the Histiocyte Society, Children's Oncology Group, and Asian Histiocytic Disorder Collaborative Group. Domains included demographics, experience treating LCH, preferred treatment in response to clinical vignettes, and opinions regarding clinical trial design. Participants included 106 pediatric attending physicians from 26 countries. Of the 89 providers with access to MAPKi, 79% have used them to treat LCH, with most reporting use outside of a clinical trial and for recurrent/refractory LCH. Nearly all participants agreed that prospective trials are needed to study MAPKi in newly diagnosed LCH, and 90% felt their institution would open such a trial. Regarding trial design, 89% would include patients with multisystem risk organ (RO) positive disease, while 47% and 21% would include multisystem or single system RO- disease, respectively. Most participants (83%) would include a trial arm combining MAPKi with chemotherapy, with 56% of these participants favoring combination therapy throughout treatment. Additionally, 43% favored including an MAPKi monotherapy arm. MAPKi are widely available and commonly utilized in pediatric LCH. While treatment practices and trial design preferences vary, there is a strong consensus regarding the need for a prospective clinical trial incorporating MAPKi into upfront therapy.
2026-07-22 | Langerhans cell histiocytosis in the adult lower gastrointestinal tract.
A female in her early 80s presented with chronic anal fissures which were unresponsive to conservative therapies. Examination was concerning for possible perianal Crohn's disease, but subsequent colonoscopy and biopsies revealed Langerhans cell histiocytosis (LCH) involving the colon and anus, diagnosed per 2022 WHO Classification of Haematolymphoid Tumours criteria and confirmed by BRAF V600E mutation. Systemic staging identified two unrelated malignancies of the breast and kidney. The patient was treated with cladribine as systemic chemotherapy, resulting in complete remission of LCH symptoms and lesions.This case illustrates key diagnostic and therapeutic considerations for clinicians: LCH can mimic inflammatory bowel disease and should be included in the differential for atypical or refractory perianal disease, especially in older adults. Histological confirmation and molecular profiling are essential for accurate diagnosis and treatment planning. Additionally, cladribine is a well-tolerated and effective option for adult LCH with gastrointestinal tract involvement. Early recognition and systemic staging are critical to guide therapy and identify potential coexisting malignancies.
2026-08-17 | Langerhans Cell Histiocytosis in Adults: A Canadian Multicenter Case Series.
Langerhans cell histiocytosis (LCH) is a rare clonal myeloid neoplasm. Canadian data on clinical characteristics, molecular profile, and treatment outcomes is limited. This study aims to report the initial experience of a Canadian rare diseases program, reflecting "real-world" diagnostic pathways, referral patterns, and treatment heterogeneity across multiple provinces. We conducted a retrospective review of patients managed in an adult-care cohort with histologically confirmed LCH diagnosed between 2000 and 2025 across multiple Canadian centers. Patients diagnosed as children and subsequently transferred to adult care were included. Clinical features, radiologic findings, histopathology, molecular testing, treatment approaches, and outcomes were collected and analyzed. Thirty-one patients were identified, with a median age at diagnosis of 42 years (range: 2-84) and a male predominance (65%). Bone (74%), lung (29%), and skin (16%) were the most commonly involved sites. Concomitant or subsequent malignancies were present in 19% of patients. Molecular testing found BRAFV600E mutations in 44% of tested patients. The most common first-line systemic therapy was cytarabine (n = 10), followed by other drugs such as hydroxyurea, vemurafenib, and cladribine. This series represents the initial experience of a Canadian rare disease referral program and captures the clinical heterogeneity and longitudinal adult care of patients with LCH across multiple provinces. Variability in treatment approaches highlights the need for collaborative prospective natural history studies and coordinated clinical trials.
2026-08-08 | Langerhans cell histiocytosis
Langerhans cell histiocytosis initially identified as an inflammatory disorder is now being referred as a rare dendritic/histiocytic neoplasm arising from dendritic cell differentiation with a heterogeneous clinical presentation manifesting in skin, bones, lungs, liver, lymph nodes, neurologic, and hematologic systems in any age group. Diagnostic work-up, staging investigations, prognostic markers, and therapeutic algorithms have seen a paradigm shift from pediatric-inspired chemotherapy regimens to a patient-tailored focused approach. Although chemotherapy is still the backbone in the era of novel circulating biomarkers and targeted agents in multisystem disease, chemoresistance and delayed neurological sequelae still remain challenges, resulting in dismal outcomes and poor quality of life.
2026-07-29 | Firm lesion consistency and whitish tissue exposure ingastrointestinal Langerhans cell histiocytosis
Keywords endoscopy upper GI tract - diagnosis and imaging (inc chromoendoscopy, NBI, iSCAN, FICE, CLE) - endoscopy lower GI tract - diagnosis and imaging (inc chromoendoscopy, NBI, iSCAN, FICE, CLE...) - Ulcers (peptic and other) Publication History Received: 25 May 2026 Accepted after revision: 15 July 2026 Article published online: 29 July 2026 © 2026. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/). Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany
2026-07-27 | Current Approaches Among Medical Providers Treating Pediatric Langerhans Cell Histiocytosis.
Most pediatric Langerhans cell histiocytosis (LCH) lesions harbor activating mutations within the mitogen-activated protein kinase (MAPK) pathway. MAPK inhibitors (MAPKi) represent a rational therapeutic strategy, though there is no consensus regarding optimal use. We sought to understand how providers currently integrate MAPKi into LCH therapy and gather input regarding potential future clinical trial designs. An online survey was distributed to members of the Histiocyte Society, Children's Oncology Group, and Asian Histiocytic Disorder Collaborative Group. Domains included demographics, experience treating LCH, preferred treatment in response to clinical vignettes, and opinions regarding clinical trial design. Participants included 106 pediatric attending physicians from 26 countries. Of the 89 providers with access to MAPKi, 79% have used them to treat LCH, with most reporting use outside of a clinical trial and for recurrent/refractory LCH. Nearly all participants agreed that prospective trials are needed to study MAPKi in newly diagnosed LCH, and 90% felt their institution would open such a trial. Regarding trial design, 89% would include patients with multisystem risk organ (RO) positive disease, while 47% and 21% would include multisystem or single system RO- disease, respectively. Most participants (83%) would include a trial arm combining MAPKi with chemotherapy, with 56% of these participants favoring combination therapy throughout treatment. Additionally, 43% favored including an MAPKi monotherapy arm. MAPKi are widely available and commonly utilized in pediatric LCH. While treatment practices and trial design preferences vary, there is a strong consensus regarding the need for a prospective clinical trial incorporating MAPKi into upfront therapy.
2026-07-22 | Langerhans cell histiocytosis in the adult lower gastrointestinal tract.
A female in her early 80s presented with chronic anal fissures which were unresponsive to conservative therapies. Examination was concerning for possible perianal Crohn's disease, but subsequent colonoscopy and biopsies revealed Langerhans cell histiocytosis (LCH) involving the colon and anus, diagnosed per 2022 WHO Classification of Haematolymphoid Tumours criteria and confirmed by BRAF V600E mutation. Systemic staging identified two unrelated malignancies of the breast and kidney. The patient was treated with cladribine as systemic chemotherapy, resulting in complete remission of LCH symptoms and lesions.This case illustrates key diagnostic and therapeutic considerations for clinicians: LCH can mimic inflammatory bowel disease and should be included in the differential for atypical or refractory perianal disease, especially in older adults. Histological confirmation and molecular profiling are essential for accurate diagnosis and treatment planning. Additionally, cladribine is a well-tolerated and effective option for adult LCH with gastrointestinal tract involvement. Early recognition and systemic staging are critical to guide therapy and identify potential coexisting malignancies.
Access all drug discovery papers and probability of success in trials forecasts:
Access all drug discovery papers and probability of success in trials forecasts:
Drug Discovery Landscape
2 orphan drug designations for Langerhans cell histiocytosis, including 1 approved therapy.
2 orphan drug designations for Langerhans cell histiocytosis, including 1 approved therapy.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
cobimetinib [Cotellic] | small molecules | FDA | 2021-04-26 | 2022-10-28 | Genentech, Inc. |
Vemurafenib | small molecules | EMA | 2016-05-30 | — | Groupe d'étude des histiocytoses |
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