Circulating senescent myeloid cells infiltrate the brain and cause neurodegeneration in histiocytic disorders.

Neurodegenerative diseases (ND) are characterized by progressive loss of neuronal function. Mechanisms of ND pathogenesis are incompletely understood, hampering the development of effective therapies. Langerhans cell histiocytosis (LCH) is an inflammatory neoplastic disorder caused by hematopoietic progenitors expressing mitogen-activated protein kinase (MAPK)-activating mutations that differentiate into senescent myeloid cells that drive lesion formation. Some individuals with LCH subsequently develop progressive and incurable neurodegeneration (LCH-ND). Here, we showed that LCH-ND was caused by myeloid cells that were clonal with peripheral LCH cells. Circulating BRAFV600E+ myeloid cells caused the breakdown of the blood-brain barrier (BBB), enhancing migration into the brain parenchyma where they differentiated into senescent, inflammatory CD11a+ macrophages that accumulated in the brainstem and cerebellum. Blocking MAPK activity and senescence programs reduced peripheral inflammation, brain parenchymal infiltration, neuroinflammation, neuronal damage and improved neurological outcome in preclinical LCH-ND. MAPK activation and senescence programs in circulating myeloid cells represent targetable mechanisms of LCH-ND.

Langerhans cell histiocytosis: NACHO update on progress, chaos, and opportunity on the path to rational cures.

Langerhans cell histiocytosis (LCH) is a myeloid neoplastic disorder characterized by lesions with CD1a-positive/Langerin (CD207)-positive histiocytes and inflammatory infiltrate that can cause local tissue damage and systemic inflammation. Clinical presentations range from single lesions with minimal impact to life-threatening disseminated disease. Therapy for systemic LCH has been established through serial trials empirically testing different chemotherapy agents and durations of therapy. However, fewer than 50% of patients who have disseminated disease are cured with the current standard-of-care vinblastine/prednisone/(mercaptopurine), and treatment failure is associated with long-term morbidity, including the risk of LCH-associated neurodegeneration. Historically, the nature of LCH-whether a reactive condition versus a neoplastic/malignant condition-was uncertain. Over the past 15 years, seminal discoveries have broadly defined LCH pathogenesis; specifically, activating mitogen-activated protein kinase pathway mutations (most frequently, BRAFV600E) in myeloid precursors drive lesion formation. LCH therefore is a clonal neoplastic disorder, although secondary inflammatory features contribute to the disease. These paradigm-changing insights offer a promise of rational cures for patients based on individual mutations, clonal reservoirs, and extent of disease. However, the pace of clinical trial development behind lags the kinetics of translational discovery. In this review, the authors discuss the current understanding of LCH biology, clinical characteristics, therapeutic strategies, and opportunities to improve outcomes for every patient through coordinated agent prioritization and clinical trial efforts.

Increased AXLhigh myeloid cells as pathognomonic marker in Langerhans cell histiocytosis and Langerin expression dependence of mTOR inhibition.

Langerhans cell histiocytosis (LCH) is characterized by an expansion and accumulation of pathological histiocytes expressing langerin (CD207) and CD1a in different organs under an inflammatory milieu. The origin of pathognomonic precursors of LCH is widely debated, but monocytes and pre-dendritic cells (pre-DC) play a significant role. Remarkably, we found an expansion of AXLhigh cells in the CD11c+ subset of patients with active LCH, which also express the pathognomonic CD207 and CD1a. Moreover, we obtained a monocyte-derived LC-like (mo-LC-like) expressing high levels of AXL when treated with inflammatory cytokine, or plasma of patients with active disease. Intriguingly, inhibiting the mTOR pathway at the initial stages of monocyte differentiation to LC-like fosters the pathognomonic LCH program, highly increasing CD207 levels, together with NOTCH1 induction. We define here that AXLhigh could also be taken as a strong pathognomonic marker for LCH, and the release of Langerin and NOTCH1 expression depends on the inhibition of the mTOR pathway.

Clofarabine monotherapy in aggressive, relapsed and refractory Langerhans cell histiocytosis.

Over 50% of patients with systemic LCH are not cured with front-line therapies, and data to guide salvage options are limited. We describe 58 patients with LCH who were treated with clofarabine. Clofarabine monotherapy was active against LCH in this cohort, including heavily pretreated patients with a systemic objective response rate of 92.6%, higher in children (93.8%) than adults (83.3%). BRAFV600E+ variant allele frequency in peripheral blood is correlated with clinical responses. Prospective multicentre trials are warranted to determine optimal dosing, long-term efficacy, late toxicities, relative cost and patient-reported outcomes of clofarabine compared to alternative LCH salvage therapy strategies.

Clinical, radiological and molecular responses to combination chemotherapy with MAPK pathway inhibition in relapsed and refractory Langerhans cell histiocytosis.

Optimal therapeutic approaches for advanced Langerhans cell histiocytosis (LCH) are not known. We assessed the safety and efficacy of combined chemotherapy with MAPK pathway inhibition in 10 patients with refractory systemic disease and/or LCH-associated neurodegeneration. Overall response rate was 9/10 (90%) for the entire cohort: 5/5 (100%) for patients with systemic disease and 6/7 (86%) for patients with central nervous system disease. BRAFV600E+ peripheral blood fraction decreased in 5/6 (83%). Toxicities included fever, skin rash, myalgias, neuropathy, cytopenias and hypocalcaemia. Prospective trials are required to optimize combination strategies, determine potential to achieve cure and compare outcomes to chemotherapy or MAPK inhibitor monotherapy.

From mutation to management: Advancing Langerhans cell histiocytosis treatment through combination therapies.

The treatment landscape for relapsed Langerhans cell histiocytosis (LCH) is fraught with uncertainty due to a scarcity of data. Karri et al.'s study provides promising evidence that combining MAPK pathway inhibitors with chemotherapy could improve outcomes, even for patients with multiple relapses. Although larger studies are needed, this approach suggests a shift towards more aggressive, potentially curative strategies in the management of LCH. Commentary on: Karri et al. Clinical, radiological and molecular responses to combination chemotherapy with MAPK pathway inhibition in relapsed and refractory Langerhans cell histiocytosis. Br J Haematol 2024;204:1882-1887.

Liver involvement with Langerhans cell histiocytosis in adults.

BACKGROUND AND AIMS: Liver involvement portends poor prognosis in adults. We aimed to characterize the clinical features, liver function tests, radiologic findings, molecular profiles, therapeutic approaches and outcomes of adults patients with Langerhans cell histiocytosis (LCH) with liver involvement. METHODS: We conducted a retrospective analysis of all adults with LCH (≥ 18 years) seen at Peking Union Medical College Hospital (Beijing, China) between January 2001 and December 2022. RESULTS: Among the 445 newly diagnosed adults with LCH, 90 patients had liver involvement at diagnosis and 22 patients at relapse. The median age was 32 years (range, 18-66 years). Of 112 evaluable patients, 108 had full liver function testing, including alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase (ALP), γ-glutamyl transpeptidase (GGT), and total bilirubin and albumin. Elevated ALP was seen in 63.0% and GGT in 86.1%; 14.8% had elevated bilirubin. Next-generation sequencing of 54 patients revealed frequent BRAFN486_P490 (29.6%), BRAFV600E (18.5%), and MAP2K1 (14.8%). OUTCOMES: After a median 40 months' follow-up (range 1-168 months), 3-year progression-free survival (PFS) and overall survival were 49.7% and 86.6% respectively. In multivariable analyses, ≥3 abnormal liver function tests (HR 3.384, 95% CI 1.550-7.388, P = .002) associated with inferior PFS; immunomodulatory drug therapy (HR 0.073, 95% CI, 0.010-0.541, P = .010) correlated with superior PFS versus chemotherapy. CONCLUSIONS: In summary, elevated GGT and ALP were common in adults with LCH liver involvement. Greater than equal to 3 abnormal liver function tests predicted poor outcomes. Immunomodulatory drug therapy was associated with favorable progression-free survival compared to chemotherapy.

Clinicopathologic Features of Gastrointestinal Tract Langerhans Cell Histiocytosis.

Gastrointestinal (GI) tract involvement by Langerhans cell histiocytosis (LCH) is rare and its clinicopathologic characteristics have only been described in case reports and small series. We reviewed hematoxylin and eosin and CD1a, S100, and Langerin immunohistochemical-stained slides from 47 patients with well-documented demographic and clinical findings. Our cases included 8 children and 39 adults, with a mean follow-up of 63 months. All pediatric patients had concurrent multisystem LCH, presented with GI symptoms, and showed nonpolypoid lesions. Seven (88%) showed multifocal GI disease, including 5 with multiple GI organ involvement. All sampled lesions from children exhibited infiltrative growth. More than half had died of the disease or manifested persistent LCH at last follow-up. Twenty-five of 39 (64%) adults had LCH involving only the GI tract (single system), with the remaining 14 (36%) exhibiting multisystem disease. Adult single-system GI LCH was typically encountered incidentally on screening/surveillance endoscopy (72%). Most exhibited isolated colorectal involvement (88%) as a solitary polyp (92%), with a well-demarcated/noninfiltrative growth pattern (70%), and excellent prognosis (100%). In comparison, adult patients with multisystem LCH more frequently presented with GI symptoms (92%, P < .001), noncolorectal GI site involvement (50%, P = .02), multifocal GI lesions (43%, P = .005), nonpolypoid lesions (71%, P < .001), infiltrative histologic growth pattern (78%, P = .04), and persistent disease (57%, P < .001). Adult patients with multisystem LCH appear to exhibit similar clinicopathologic features to those of pediatric patients. These results demonstrated that adults with single-system LCH involving the GI tract have an excellent prognosis, whereas multisystem LCH occurring at any age carries an unfavorable prognosis. High-risk features of GI LCH include pediatric age, GI symptomatology, noncolorectal GI involvement, multifocal GI disease, nonpolypoid lesions, and infiltrative growth pattern.

Identification and characterization of stromal-like cells with CD207+/low CD1a+/low phenotype derived from histiocytic lesions - a perspective in vitro model for drug testing.

BACKGROUND: Histiocytoses are rare disorders manifested by increased proliferation of pathogenic myeloid cells sharing histological features with macrophages or dendritic cells and accumulating in various organs, i.a., bone and skin. Pre-clinical in vitro models that could be used to determine molecular pathways of the disease are limited, hence research on histiocytoses is challenging. The current study compares cytophysiological features of progenitor, stromal-like cells derived from histiocytic lesions (sl-pHCs) of three pediatric patients with different histiocytoses types and outcomes. The characterized cells may find potential applications in drug testing. METHODS: Molecular phenotype of the cells, i.e. expression of CD1a and CD207 (langerin), was determined using flow cytometry. Cytogenetic analysis included GTG-banded metaphases and microarray (aCGH) evaluation. Furthermore, the morphology and ultrastructure of cells were evaluated using a confocal and scanning electron microscope. The microphotographs from the confocal imaging were used to reconstruct the mitochondrial network and its morphology. Basic cytophysiological parameters, such as viability, mitochondrial activity, and proliferation, were analyzed using multiple cellular assays, including Annexin V/7-AAD staining, mitopotential analysis, BrdU test, clonogenicity analysis, and distribution of cells within the cell cycle. Biomarkers potentially associated with histiocytoses progression were determined using RT-qPCR at mRNA, miRNA and lncRNA levels. Intracellular accumulation of histiocytosis-specific proteins was detected with Western blot. Cytotoxicyty and IC50 of vemurafenib and trametinib were determined with MTS assay. RESULTS: Obtained cellular models, i.e. RAB-1, HAN-1, and CHR-1, are heterogenic in terms of molecular phenotype and morphology. The cells express CD1a/CD207 markers characteristic for dendritic cells, but also show intracellular accumulation of markers characteristic for cells of mesenchymal origin, i.e. vimentin (VIM) and osteopontin (OPN). In subsequent cultures, cells remain viable and metabolically active, and the mitochondrial network is well developed, with some distinctive morphotypes noted in each cell line. Cell-specific transcriptome profile was noted, providing information on potential new biomarkers (non-coding RNAs) with diagnostic and prognostic features. The cells showed different sensitivity to vemurafenib and trametinib. CONCLUSION: Obtained and characterized cellular models of stromal-like cells derived from histiocytic lesions can be used for studies on histiocytosis biology and drug testing.

Circulating monocytes decrease significantly following disease-directed therapy and may reflect disease expansion in Langerhans Cell Histiocytosis.

We aimed to examine the association between relative monocytosis and the recurrence of pulmonary Langerhans Cell Histiocytosis. Clinical, laboratory, radiographic and treatment data for 86 patients with a histopathological diagnosis of Langerhans Cell Histiocytosis over a 20-year duration. Parameters such as biological sex, age at diagnosis, time to diagnosis, molecular diagnostic data and imaging were collected. Treatment responses were assessed predominantly through radiography, with RECIST 1.1 criteria applied to MRI or CT scans and PERCIST utilized for serial PET imaging. Investigators also assessed peripheral blood absolute monocyte count at various time points, including initial diagnosis and the most recently available value. While peripheral blood absolute monocyte count between the earliest assessed timepoint and latest value did not differ, the mean value on progression (0.94 K/µL), however, was significantly higher than that following re-institution of therapy (0.31, p = 0.000794. Our observation of relative monocytosis on LCH disease progression may be related to an increase in circulating LCH on disease progression or from increased monocyte production for later differentiation into mature dendritic cells that participate in MHC Class 1 upregulation. This trend is especially evident in pulmonary LCH which is incited by tissue trauma and irritation by environmental factors. The phenomena observed in our study parallel other non-LCH cohorts, specifically in published findings from our own group in patients with Rosai Dorfman and Erdheim Chester Disease. To further elucidate the molecular underpinnings of LCH and explore the etiology of this monocyte trend, expanded integrated genomic-transcriptomic sequencing analyses to evaluate the molecular character of LCH and ultimately clarify the origin of this monocyte trend are in progress. These studies are poised to offer invaluable insight to the molecular mechanisms underlying LCH, specifically as they pertain to monocyte signaling and differentiation.

Manifestations and outcomes of digestive tract involvement in adult Langerhans cell histiocytosis.

Langerhans cell histiocytosis (LCH) is a heterogeneous histiocytosis characterized by proliferation of Langerhans cells. While less common, manifestations of digestive tract involvement in LCH remain largely unrevealed. We conducted a retrospective analysis of demographics, clinical, endoscopic, genetic and follow-up data from 13 adult patients with pathologically confirmed gastrointestinal involvement of LCH (LCH-GI), in a single-center cohort of 465 patients. Digestive tract involvement was observed in 2.80% of LCH patients. At LCH-GI diagnosis, 7 patients (53.8%) had unifocal lesions, and 6 patients (46.2%) had multisystem disease. 6 patients (46.2%) experienced no gastrointestinal symptoms at LCH-GI onset, while others were symptomatic. Stomach was most commonly affected (61.5%), followed by esophagus (23.1%), colon (7.7%) and anus (7.7%). Endoscopic findings varied among 12 patients, including submucosal bulge (8 patients, 66.7%) and non-bulging lesions (4 patients, 33.3%) such as erosions, coarse granular mucosa, and regional abnormal coloration. Among 8 patients with genetic analysis, BRAFV600E mutation was detected in 5 patients (62.5%). The estimated 1-year overall survival rate was 91.7%. Progression-free survival of patients with submucosal bulges under endoscopy was significantly better than those with non-bulging lesions. This study presents 13 cases of LCH with digestive tract involvement. We emphasize the importance of endoscopy and biopsy for pathological examination of lesions such as submucosal bulges and erosions under endoscopy to assist in early detection of LCH. Comprehensive systemic assessment and regular endoscopic monitoring are essential in patient management. Treatment should be individualized with dynamic adjustments during follow-up.

Langerhans cell histiocytosis in children born after assisted reproductive technology.

RESEARCH QUESTION: Are children born after assisted reproductive technology (ART) at higher risk of developing Langerhans cell histiocytosis (LCH)? DESIGN: Records of children born after ART recorded by the UK Human Fertilisation & Embryology Authority were linked to National Registry of Childhood Tumours records to determine the number of children developing LCH. Calculated person-years at risk were used in conjunction with the incidence of LCH in the general population to determine the expected number of cases if the cohort had the same incidence as the general population with similar age and sex, over the same calendar years. The standardized incidence ratio (SIR) was derived as the ratio of observed to expected cases. Exact 95% CI were calculated. RESULTS: In total, 118,155 children born after ART contributed 796,633 person-years follow-up (average follow-up 6.74 years). Eight cases of LCH were identified, compared with 3.75 cases expected (SIR 2.135, 95% CI 0.92-4.21; P = 0.074). Significantly more cases were associated with intracytoplasmic sperm injection (ICSI) (SIR 4.02, 95% CI 1.31-9.39) and male factor infertility (SIR 5.41, 95% CI 1.47-13.84). Most cases of LCH had single-system disease (n = 6). CONCLUSIONS: This study found that significantly more cases of LCH were identified in children born after ICSI and in children whose parents had male factor infertility. A non-significant excess of cases in children born after ART was identified. Absolute excess risk was small. Given the rarity of LCH and the small number of cases included in this large cohort, further studies into the risk of LCH in children born after ART are indicated.

The plasma-soluble CSF1R level is a promising prognostic indicator for pediatric Langerhans cell histiocytosis.

Langerhans cell histiocytosis (LCH) is a rare hematologic neoplasm characterized by the clonal proliferation of Langerhans-like cells. Colony-stimulating factor 1 receptor (CSF1R) is a membrane-bound receptor that is highly expressed in LCH cells and tumor-associated macrophages. In this study, a soluble form of CSF1R protein (sCSF1R) was identified by plasma proteome profiling, and its role in evaluating LCH prognosis was explored. We prospectively measured plasma sCSF1R levels in 104 LCH patients and 10 healthy children using ELISA. Plasma sCSF1R levels were greater in LCH patients than in healthy controls (p < .001) and significantly differed among the three disease extents, with the highest level in MS RO+ LCH patients (p < .001). Accordingly, immunofluorescence showed the highest level of membrane-bound CSF1R in MS RO+ patients. Furthermore, the plasma sCSF1R concentration at diagnosis could efficiently predict the prognosis of LCH patients treated with standard first-line treatment (AUC = 0.782, p < .001). Notably, dynamic monitoring of sCSF1R levels could predict relapse early in patients receiving BRAF inhibitor treatment. In vitro drug sensitivity data showed that sCSF1R increased resistance to Ara-C in THP-1 cells expressing ectopic BRAF-V600E. Overall, the plasma sCSF1R level at diagnosis and during follow-up is of great clinical importance in pediatric LCH patients.

BRAF-V600E mutations in plasma and peripheral blood mononuclear cells correlate with prognosis of pediatric Langerhans cell histiocytosis treated with first-line therapy.

BACKGROUND: The clinical relevance of BRAF-V600E alleles in peripheral blood mononuclear cells (PBMCs) and the prognostic impact of the mutants in cell-free (cf) and PBMC DNAs of Langerhans cell histiocytosis (LCH) have not been fully clarified in pediatric LCH. METHODS: We retrospectively determined the levels of BRAF-V600E mutation in paired plasma and PBMC samples at the time of diagnosis of LCH. Subsequently, we performed a separate or combined analysis of the clinical and prognostic impact of the mutants. RESULTS: We assessed BRAF-V600E mutation in peripheral blood from 94 patients of childhood LCH. Our data showed that cfBRAF-V600E was related to young age, multiple-system (MS) disease, involvements of organs with high risk, increased risk of relapse, and worse progression-free survival (PFS) of patients. We also observed that the presence of BRAF-V600E in PBMCs at baseline was significantly associated with MS LCH with risk organ involvement, younger age, and disease progression or relapse. The coexisting of plasma(+)/PBMC(+) identified 36.2% of the patients with the worst outcome, and the hazard ratio was more significant than either of the two alone or neither, indicating that combined analysis of the mutation in plasma and PBMCs was more accurate to predict relapse than evaluation of either one. CONCLUSIONS: Concurrent assessment of BRAF-V600E mutation in plasma and PBMCs significantly impacted the prognosis of children with LCH. Further prospective studies with larger cohorts need to validate the results of this study.

Cerebellar peduncle damage in Langerhans cell histiocytosis-associated neurodegenerative disease revealed by diffusion tensor imaging.

PURPOSE: To confirm the hypothesis that brain white matter damage is involved in the pathogenesis and disease progression of Langerhans cell histiocytosis (LCH)-associated neurodegenerative disease (ND), we aimed to analyze pediatric patients with LCH using diffusion tensor imaging (DTI). METHODS: We enrolled 33 patients with LCH and obtained 33 DTI datasets. Using DTI-based tractography, fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD) were measured in the cerebral and cerebellar white matter tracts. The participants were divided into three groups-non-ND, ND without clinical symptoms (r-ND), and ND with clinical symptoms (c-ND)-according to their clinical status during the examination with DTI. We compared the DTI parameters in white matter tracts were compared among the three groups. RESULTS: In the order of non-ND, r-ND, and c-ND groups, the FA in superior cerebellar peduncle (SCP) and middle cerebellar peduncle (MCP) significantly decreased, the ADC, AD, and RD of MCP, and the RD of SCP were significantly elevated (FA-SCP; p < 0.001, FA-MCP; p = 0.026, ADC-MCP; p < 0.001, AD-MCP; p = 0.002, RD-MCP; p = 0.003, and RD-SCP; p = 0.018). Furthermore, in the simple linear regression analysis, the FA, ADC, AD, and RD values in the MCP and the FA value in the SCP were significantly influenced by the presence of neurological symptoms and ND findings on MRI (all p < 0.001). CONCLUSION: In LCH-ND, we identified microstructural damage in the SCP and MCP. DTI parameters in these tracts may help monitor LCH-ND; therefore, future studies are required to validate these results in a large cohort.

Concurrent Langerhans cell histiocytosis and acute myeloid leukemia: A rare presentation of a rare case.

A 72-year-old woman with no significant past medical history was admitted to the hospital for new-onset of leukocytosis with neutropenia, anemia, and thrombocytopenia, as well as a pruritic skin eruption. She was found to have acute myeloid leukemia (AML) with myelomonocytic differentiation. Her skin eruption consisted of widespread hemorrhagic crusted papules on the scalp and trunk. A skin biopsy was performed, which revealed a proliferation of mononuclear cells in the dermis with prominent epidermotropism and positive expression of CD1a and langerin (CD207), supporting a diagnosis of Langerhans cell histiocytosis (LCH). LCH is an uncommon proliferative disorder of activated Langerhans cells, which generally presents in children. In adults, it is exceptionally infrequent. Associated malignancies and rare reports of AML developing in subsequent years after an initial presentation of LCH have been described. Here we present an unusual concurrent presentation of LCH and AML in an adult.

Dermoscopy and reflectance confocal microscopy finding of different anatomic sites of Langerhans cell histiocytosis.

BACKGROUND: Recognizing Langerhans cell histiocytosis (LCH) might be a challenge due to its rarity. Reflectance confocal microscopy (RCM) and dermoscopy were emergent promising non-invasive technique as auxiliary tools in diagnosis of different skin conditions. However, the RCM and dermoscopic features of LCH had been less investigated. To reveal the common RCM and dermoscopic features of LCH. MATERIALS AND METHODS: Forty cases of LCH were retrospectively analyzed according to age, locations, clinical, RCM, and dermoscopic features from September 2016 to December 2022. To reveal the differences and common in clinical, RCM, and dermoscopic features that occur in different anatomic location. RESULTS: In the study, sites of predilection include the trunk 31/40 (77.5%), extremity 21/40 (52.5%), face 14/40 (35%), scalp 11/40 (27.5%), vulvar 4/40 (10%), and nail 2/40 (5%). All LCHs had the common RCM features. There were significant differences in clinical and dermoscopic features for age and lesion anatomic site. The common dermoscopic features for scalp, face, trunk, and extremity were the erythematous scaly rash, purplish-red globules or patches, scar-like streaks with ectatic vessels. While the features for nail LCH were purpuric striae, onycholysis and purulent scaly rash, and the erosive erythematous plaque and purulent scaly rash for vulvar LCH. The common RCM features of all LCH showed a focal highly reflective dense image in the surface keratin layer, epidermis architectural disarray, obscuration of dermo-epidermal junction, numerous polygonal, large, medium reflective, short dendrites cells in the epidermis, and dermis. All LCH involving the vulvar and nail did not manifest skin lesions. CONCLUSION: RCM and dermoscopy showed promising value for diagnosis and differentiation of LCH.

Expanding horizons: lung transplantation for non-IPF interstitial lung diseases.

OBJECTIVE: Interstitial lung diseases (ILDs) are diverse pulmonary disorders marked by diffuse lung inflammation and fibrosis. The variability in characteristics and treatment approaches complicates diagnosis and management. In advanced cases requiring transplantation, determining indications and selecting suitable candidates presents additional challenges. METHODS: Of all patients with non-IPF ILD between December 2016 to December 2022 were analyzed retrospectively. Patients were categorized into two groups: transplanted patients and deceased patients on the waiting list. Clinical data and survival outcomes were compared between groups. RESULTS: Of the 43 patients, 20 underwent lung transplantation while 23 died awaiting transplantation. Waiting list mortality was 53.4%, with median waiting times similar between groups (3 months for transplant patients and 6 months for those on the waiting list). There were no significant differences between groups in age, gender, height, BMI, 6-minute walk test (6MWT), or forced vital capacity (FVC). The prevalence of pulmonary hypertension (PH) was 76.7% in right heart catheterizations, similar in both groups. One single and 19 bilateral lung transplants were performed. Overall, 13 of the 20 patients survived to discharge from the hospital. One-year mortality was 7/20 (35%). The median follow-up was 34 months, with a 1-year conditional survival of 90.9% at 3 years and 70.7% at 5 years. CONCLUSIONS: This study underscores the importance of further research into non-IPF ILDs. Lung transplantation remains a viable option that can significantly enhance both the quality and longevity of life for patients with advanced ILD.

Langerhans cell histiocytosis of the thyroid mimicking thyroiditis in a boy: a case report and literature review.

BACKGROUND: Langerhans cell histiocytosis affecting the thyroid commonly presents with nonspecific clinical and radiological manifestations. Thyroid Langerhans cell histiocytosis is typically characterized by non-enhancing hypodense lesions with an enlarged thyroid on computed tomography medical images. Thyroid involvement in LCH is uncommon and typically encountered in adults, as is salivary gland involvement. Therefore, we present a unique pediatric case featuring simultaneous salivary and thyroid involvement in LCH. CASE PRESENTATION: A 3-year-old boy with complaints of an anterior neck mass persisting for 1 to 2 months, accompanied by mild pain, dysphagia, and hoarseness. A physical examination revealed a 2.5 cm firm and tender mass in the left anterior neck. Laboratory examinations revealed normal thyroid function test levels. Ultrasonography revealed multiple heterogeneous hypoechoic nodules with unclear and irregular margins in both lobes of the thyroid. Contrast-enhanced neck computed tomography revealed an enlarged thyroid gland and bilateral submandibular glands with non-enhancing hypointense nodular lesions, and multiple confluent thin-walled small (< 1.5 cm) cysts scattered bilaterally in the lungs. Subsequently, a left thyroid excisional biopsy was performed, leading to a histopathological diagnosis of LCH. Immunohistochemical analysis of the specimen demonstrated diffuse positivity for S-100, CD1a, and Langerin and focal positivity for CD68. The patient received standard therapy with vinblastine and steroid, and showed disease regression during regular follow-up of neck ultrasonography. CONCLUSIONS: Involvement of the thyroid and submandibular gland as initial diagnosis of Langerhans cell histiocytosis is extremely rare. It is important to investigate the involvement of affected systems. A comprehensive survey and biopsy are required to establish a definitive diagnosis.

Clinical features and treatment outcomes of liver involvement in paediatric Langerhans cell histiocytosis.

Langerhans cell histiocytosis (LCH) is the most common histiocytic disorder in children, and liver involvement in LCH is rare. This retrospective study reported the clinical features and prognosis of patients with hepatic LCH. Liver involvement was defined by histopathological findings, liver dysfunction or abnormalities, or ultrasound imaging. A total of 130 patients (14.5%) with hepatic LCH out of 899 in the LCH population were enrolled. Patients with liver involvement had greater frequencies of skin, lung, hearing system, and haematologic system involvement, and hemophagocytic lymphohistiocytosis (P<0.001, 0.001, 0.002, 0.009, and <0.001, respectively). Overall survival and progression-free survival were lower in LCH patients with liver involvement than in those without liver involvement (P<0.001 and <0.001). In patients with liver involvement, the overall survival (OS) and progression-free survival (PFS) rates were lower in patients with cholangitis than in those without cholangitis (P<0.020 and 0.030). For the treatment response, the response rate of hepatic LCH patients to initial first-line therapy (n=89) was 22.5%. However, there was no significant difference in the response rate or recurrence rate between patients who shifted from first-line treatment to second-line treatment (n=29) or to targeted therapy (n=13) (P=0.453 and 1.000). The response rate of hepatic LCH patients who received initial second-line therapy (n=13) was 38.5%. Two of these patients subsequently experienced bone recurrence. The response rate of hepatic LCH patients who received initial targeted therapy (n=16) was 75.0%. Three patients subsequently experienced recurrence, including 2 in the bone and 1 in the liver and skin. A total of 39.3% of patients who received second-line treatment had severe myelosuppression (grade III-IV), and 50.8% had varying degrees of gastrointestinal events, whereas there was no severe toxicity in patients who received first-line treatment and targeted therapy. Four patients underwent liver transplantation because of liver cirrhosis. The patients' liver disease improved within a follow-up period of 18-79 months. This study demonstrated that LCH with liver involvement, especially cholangitis, indicates a poor prognosis. Targeted therapy provides a good treatment response and less toxicity. However, it may relapse after withdrawal. Liver transplantation is still a reliable salvage option for patients with end-stage liver disease.