Pulmonary involvement in pediatric-onset multisystem Langerhans cell histiocytosis: effect on course and outcome

Childhood interstitial lung diseases: current understanding of the classification and imaging findings

Childhood interstitial lung diseases (chILDs) encompass a diverse group of disorders with a high mortality rate and severe respiratory morbidities. Recent investigations have revealed that the classification of adult ILDs is not valid for chILDs, particularly for ILDs of early onset. Therefore, Children's Interstitial Lung Disease Research Cooperative of North America proposed a new classification of chILDs for affected children under 2 years of age, and later another classification for affected individuals between 2 and 18 years of age. In this review, we provide an overview of the imaging findings of chILDs by classification. Most infantile ILDs have unique clinical, radiological, and molecular findings, while the manifestation of pediatric ILDs overlaps with that of adult ILDs.

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.

Pulmonary involvement in children with Langerhans cell histiocytosis

BACKGROUND

Pulmonary Langerhans cell histiocytosis (pLCH) is a rare disease, mostly a component of multisystemic LCH. We aimed to investigate the clinical features and treatment results in children with pLCH.

METHODS

We retrospectively reviewed the clinical, radiological, and treatment data of 37 patients with pLCH, diagnosed from 1974 to 2022.

RESULTS

10% (n=37) of 367 patients with LCH had lung involvement. The median age was 1.8 years (range: 0.4 & 17.7) with a male-to-female ratio of 2.3. At admission 29.7% (n=11) presented with respiratory symptoms. Imaging showed a spectrum from nodular opacities to multiple cysts. All but one patient had multisystem disease. Twenty-nine received vinblastine-containing therapy. Ten-year event-free (EFS) and overall survival (OS) rates were 47.8% and 63.3%, respectively. In children younger and older than two years of age, the 10-year EFS was 53.3% vs. 40.2% and the 10-year OS was 58.7% vs. 68.8%, respectively. In children with and without risk organ involvement, 10-year EFS was 51.9% vs. 46.3% and 10-year OS was 51.9% vs. 73.7%.

CONCLUSIONS

Lung and multisystem involvement are significant concerns in LCH, highlighting the need for careful management to reduce morbidity and mortality.

Pediatric pulmonary multisystem langerhans cell histiocytosis: does lung lesion severity affect the outcome?

BACKGROUND

The pediatric pulmonary multisystem Langerhans cell histiocytosis (PPM LCH) is associated with either low risk or high risk organ(s). The nodulo-cystic lung lesions although pathognomonic, yet are very variable in severity and remain a source of controversy in certifying pulmonary LCH diagnosis. The study aimed to examine the prognostic value of clinical respiratory manifestations and radiological lung lesions severity. This is through associating a CT chest triad of bilateral, extensive and diffuse lesions. It is a retrospective study of 350 LCH patients who received systemic treatment at Children's Cancer Hospital Egypt during the period from 2007 to 2020.

RESULTS

Sixty-seven patients (67/350-19.1%) had PPM LCH at presentation. Severe lung lesions were present in 24 of them. The median follow-up period was 61 months (IQR: 3.4-8.3). The 5-year overall survival (OS) and event free survival (EFS) was 89% and 56.6% respectively. The EFS, for severe radiological lesions triad was 38% ± 20.7 versus 66% ± 16.2 for non-severe lesions triad p 0.002, while for presence of chest X-ray changes 27% ± 22.344 versus absence of chest X ray changes 66% ± 14.7 p 0.001, for clinical respiratory manifestations 13% ± 13.9 versus none 62% ± 22.9 p < 0.001, for RO- with severe lung lesions 47% ± 30.4 versus RO- without severe lung lesions 69% ± 5.9 p 0.04. There was a tendency for the independent prognostic impact of severe lung involvement; aHR = 1.7 (95% CI 0.92-3.13, p = 0.09).

CONCLUSION

Although the lung is a low -risk organ per se in LCH, our study demonstrates a non negligeable prognostic impact of severe lung involvement in the risk stratification of pediatric LCH. This warrants further study and external validation.

Serum levels of soluble interleukin 2 receptor (sIL-2R), tumor necrosis factor-alpha (TNF-α), and immunoglobulin M are correlated with the disease extent in childhood Langerhans cell histiocytosis

PURPOSE

This study aimed to identify peripheral parameters associated with the severity of Langerhans cell histiocytosis (LCH) and to look for indicators associated with improvement in LCH patients with risk-organ involvement.

METHODS

This study enrolled LCH patients who were assessed as active disease-better (AD-B) after treatment. Patients were divided into the single system (SS) group, multisystem disease without risk-organ involvement (RO- MS) group, and multisystem disease with risk-organ involvement (RO + MS) group. Serum cytokines, immunoglobulins, and lymphocyte subsets were measured at admission for all three groups. Changes in these indicators after treatment were also analyzed.

RESULTS

From January 2015 to January 2022, a total of 46 patients were recruited in the present study, including 19 patients (41.3%) in the SS group, 16 patients (34.8%) in the RO- MS group, and 11 patients (23.9%) in the RO + MS group. Serum levels of soluble interleukin 2 receptor (sIL-2R) (> 912.5 U/mL), tumor necrosis factor-alpha (TNF-α) (> 20.3 pg/mL), and immunoglobulin M (< 1.12 g/L) were found to be effective in identifying patients in the RO + MS group. Furthermore, the levels of sIL-2R (SS vs RO + MS: P = 0.002, RO- MS vs RO + MS: P = 0.018) and CD8 + T-cell count (SS vs RO + MS: P = 0.028) significantly declined in the RO + MS group after treatment, indicating disease improvement.

CONCLUSIONS

The levels of sIL-2R and TNF-α were positively correlated with the extent of disease, while the levels of IgM were negatively correlated with the extent of disease. Additionally, the levels of sIL-2R and CD8 + T-cell count could serve as useful indicators to evaluate the treatment response in RO + MS-LCH patients.

Intensification of treatment with vinca alkaloid does not improve outcomes in pediatric patients with Langerhans cell histiocytosis: results from the JPLSG LCH-12 study

Chemotherapy with cytarabine, vincristine (VCR), and prednisolone has achieved low mortality rates in pediatric patients with Langerhans cell histiocytosis (LCH). However, relapse rates remain high, making event-free survival (EFS) rates unsatisfactory. A nationwide clinical trial, LCH-12, tested a modified protocol in which the early maintenance phase was intensified with increasing dosages of VCR. Patients newly diagnosed with multifocal bone (MFB) or multisystem (MS) LCH and aged < 20 years at diagnosis were enrolled between June 2012 and November 2017. Of the 150 eligible patients, 43 with MFB were treated for 30 weeks and 107 with MS LCH were treated for 54 weeks. One patient with MS LCH died of sepsis during the induction phase. The 3-year EFS rates among patients with MFB LCH, risk organ (RO)-negative MS LCH, and RO-positive MS LCH were 66.7% (95% confidential interval [CI], 56.5-77.0%), 66.1% (95% CI 52.9-76.4%), and 51.1% (95% CI 35.8-64.5%), respectively, similar to previously observed rates. EFS rates were significantly lower in patients with disease activity scores > 6 than in those with scores ≤ 6. The strategy that included more intense treatment with VCR was not effective. Other strategies are required to improve outcomes in patients with pediatric LCH.

Langerhans Cell Histiocytosis in Children: Literature Review

Relevant information on Langerhans cell histiocytosis development and course in children is presented. The current concepts of disease pathogenesis, principles of its severity evaluation, patients stratification into risk groups, as well as of clinical course features are described. Modern approaches to the disease treatment via targeted therapy are summarized and analyzed. 

Integrated imaging of systemic Langerhans cell histiocytosis in an infant

Langerhans cell histiocytosis (LCH) is a myeloid neoplasm characterized by a clonal proliferation of CD1a+/CD207+ dendritic cells. Although individuals of any age can be affected, the disease is most common in infants younger than 5 years of age, especially males. A wide range of manifestations, from asymptomatic to aggressive, have been described, along with multiorgan involvement. Even though the majority of bone lesions are observed, skin, lymph nodes, brain and lungs can also be involved. The involvement of hematopoietic system, including bone marrow, liver and spleen, is less frequent yet associated with worse prognosis, due to a worse treatment response. Diagnosis of LCH is based on the integration of clinical, laboratory, and radiological data; however, only histopathological examination might confirm it. As far as the spleen involvement is concerned, according to literature, it has been reported in about 15% patients with multisystem involvement, nonetheless only a few cases show parenchymal lesions. The present study reports the case of an infant with LCH with multisystem involvement, including bone, skin, liver, and spleen, with evidence of parenchymal lesions.

Multisystem Langerhans Cell Histiocytosis in Younger Infants First Presenting in Skin: A Case Series

Objectives—To investigate the clinical characteristics, managements, outcome, and evaluate the risk factors of Multisystem (MS) Langerhans Cell Histiocytosis (LCH) with diverse skin lesions as the first sign in four young infants. Methods—Their clinical features, disease progression, therapy, and outcomes were reviewed and analyzed retrospectively. Results—The average onset age of skin lesions was about 2 months. Cases 1 and 2 had risk organs involved (RO+) and a lack of bone lesions, and progression could not be reversed by systemic chemotherapy. They both died eventually. Cases 3 and 4 (RO–) had bone involvement and were given systemic chemotherapy for a prolonged duration. Unluckily, Case 3 had a recurrence 2 years later, while Case 4’s recurrence happened nearly one year later, and diabetes insipidus one and a half years later. They both survived and are still in remission. Conclusion—MS-LCH infants with a low age of the first presentation in the skin are prone to dissemination, while RO+ is associated with high mortality. In addition, bone involvement may be a protective factor. Immunohistochemical examination of skin tissue facilitates correct early diagnosis, and adequate follow-up is necessary.

Head and Neck Langerhans Cell Histiocytosis in Children

PURPOSE

Controversy exists among head and neck surgical specialties regarding management of Langerhan's Cell Histiocytosis (LCH). The purpose of this study was to evaluate diagnosis, management, and treatment outcomes in children with LCH of the head and neck.

METHODS

This is a retrospective cohort study of children with LCH of the head and neck who presented to Children's Healthcare of Atlanta hospital from 2009 to 2021. The independent variables were demographic information, lesion locations, clinical presentation, radiographic findings, diagnostic workup, treatment, and length of follow-up. The patients were grouped based on these variables. The outcome variable was disease reactivation. Descriptive statistics were calculated.

RESULTS

There were 3 presentations of LCH of the head and neck. Group 1 presented as a lesion in 1 system without CNS risk (SS-). There were 24 patients with an average age of 10 years. Lesions were located in calvaria and/or mandible. Majority of the patients were treated with only debridement. Two of the patients experienced reactivation. Group 2 presented as a lesion in 1 system with CNS risk (SS+). There were 30 patients with an average age of 6 years. Common locations were temporal bone and/or orbit. These patients present with recurrent ear infections and ptosis. Majority of the patients were treated with chemotherapy (n = 28). One patient had disease reactivation. Group 3 presented with multisystem involvement. There were 13 patients with an average age of 2 years. LCH was found in skin and the lymphatic system. Imaging demonstrated extracranial organ involvement. All of them were treated with chemotherapy. There was 40% reactivation of LCH.

CONCLUSIONS

Treatment of LCH depends on presentation. SS- subgroup can be adequately treated via surgical debridement. SS+ and multisystem groups benefit from an early disease diagnosis and require chemotherapy.

Clinical features and treatment of Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is caused by the expansion of CD1a+/CD207+ cells and is characterised by a wide spectrum of organ involvement and dysfunction, affecting all ages. While almost all organs and systems can be affected, only the involvement and dysfunction of liver, spleen, and haematopoietic system influence survival. The LCH pathogenic cells are defined by universal activation of the mitogen-activated protein kinase (MAPK) signalling pathway. The most common alteration is a somatic BRAFV600E mutation, which is present in approximately two-thirds of the cases, followed by MAP2K1 mutations. Treatment of LCH is risk-adapted; patients with single lesions may respond well to local treatment, whereas patients with multi-system disease require systemic chemotherapy. While survival for patients without organ dysfunction is excellent, mortality rates for patients with organ dysfunction may reach 20%. Despite progress made in the treatment of LCH, disease reactivation rates remain above 30%, and standard second-line treatment has yet to be established. Long-term effects, including neuroendocrine dysfunction and neurodegeneration, represent a major challenge for survivors. Treatment with BRAF or MEK inhibitors results in immediate responses, but reactivations are very common after discontinuation. Their role as single agents and in combination with chemotherapy is being explored.

Clofarabine monotherapy in two patients with refractory Langerhans cell histiocytosis

Background

Better therapeutic options other than conventional chemotherapy for pediatric patients with refractory Langerhans cell histiocytosis (LCH) remain undetermined.

Case

We successfully treated two patients with refractory and risk organ negative LCH with clofarabine (CLO) monotherapy after recurrence. We administered total 23 courses of CLO monotherapy in patient 1 and 4 courses in patient 2. Both patients had distinct clinical manifestations but achieved a durable complete response with acceptable adverse effects of transient myelosuppression. CLO monotherapy was still effective when he had the second recurrent lesion after first completion of CLO in patient 1. We could discontinue prednisolone to control his refractory inflammation of LCH after completing CLO chemotherapy in patient 2.

Conclusion

Although large‐scale studies are warranted, CLO monotherapy could be a therapeutic option for high efficacy and feasibility besides other intensive combination chemotherapies or allogeneic hematopoietic stem cell transplantation for refractory LCH without risk organ involvement in children.

Histiocytic disorders

The historic term 'histiocytosis' meaning 'tissue cell' is used as a unifying concept for diseases characterized by pathogenic myeloid cells that share histological features with macrophages or dendritic cells. These cells may arise from the embryonic yolk sac, fetal liver or postnatal bone marrow. Prior classification schemes align disease designation with terminal phenotype: for example, Langerhans cell histiocytosis (LCH) shares CD207+ antigen with physiological epidermal Langerhans cells. LCH, Erdheim-Chester disease (ECD), juvenile xanthogranuloma (JXG) and Rosai-Dorfman disease (RDD) are all characterized by pathological ERK activation driven by activating somatic mutations in MAPK pathway genes. The title of this Primer (Histiocytic disorders) was chosen to differentiate the above diseases from Langerhans cell sarcoma and malignant histiocytosis, which are hyperproliferative lesions typical of cancer. By comparison LCH, ECD, RDD and JXG share some features of malignant cells including activating MAPK pathway mutations, but are not hyperproliferative. 'Inflammatory myeloproliferative neoplasm' may be a more precise nomenclature. By contrast, haemophagocytic lymphohistiocytosis is associated with macrophage activation and extreme inflammation, and represents a syndrome of immune dysregulation. These diseases affect children and adults in varying proportions depending on which of the entities is involved.

Recurrent pulmonary infections as the first presentation of Letterer Siwe disease

Langerhans cell histiocytosis (LCH) is a rare disease of unknown etiology that affects several organs. The fatal type of Langerhans cell histiocytosis is called Letterer Siwe disease (LSD) which is multisystem with a poor prognosis. Herein, we report a 20-month-old male who was admitted for recurrent pulmonary infections at the age of 10 months. Diagnostic workup revealed a Letterer-Siwe disease. The patient was treated with a good response.

Update on Pulmonary Langerhans Cell Histiocytosis

Pulmonary Langerhans cell (LC) histiocytosis (PLCH) has unknown cause and is a rare neoplastic disorder characterized by the infiltration of lungs and various organs by bone marrow-derived Langerhans cells with an accompanying strong inflammatory response. These cells carry somatic mutations of BRAF gene and/or NRAS, KRAS, and MAP2K1 genes, which cause activation of the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling pathway. PLCH occurs predominantly in young smokers, without gender predominance. Lungs might be involved as an isolated organ or as part of a multiorgan disease. High-resolution computed chest tomography plays an outstanding role in PLCH diagnosis. The typical radiological picture of PLCH is the presence of small intralobular nodules, “tree in bud” opacities, cavitated nodules, and thin- and thick-walled cysts, frequently confluent. Histological examination of the lesion and demonstration of characteristic eosinophilic granulomas with the presence of LCs that display antigen CD1a or CD207 in immunohistochemistry are required for definite diagnosis. Smoking cessation is the most important recommendation for PLCH patients, but treatment of progressive PLCH and multisystem disease is based on chemotherapy. Recently, new targeted therapies have been implemented.

Langerhans cell histiocytosis in children: A retrospective case series of 126 cases

BACKGROUND/OBJECTIVES

Langerhans cell histiocytosis (LCH), a rare neoplasm of hematopoietic myeloid precursor cells, is clinically characterized by spontaneously resolving lesions to a progressive life-threatening multisystem disorder. Diagnosing LCH in children is challenging as it mimics other skin disorders. This study describes the varied clinical presentation and disease course in children less than 18 years diagnosed with LCH.

METHODS

We performed a retrospective observational study of all cases diagnosed with LCH presenting to a children's hospital in the last 26 years. Data on history, cutaneous and systemic examination, and laboratory evaluation performed, were recorded.

RESULTS

A total of 126 children diagnosed with LCH were included in the study. There were 68% cases limited only to skin, and 32% children with multisystem involvement at the initial presentation. Scaly papules were the most common morphologic finding in skin. The skeletal system was the second most common organ system to be affected. Failure to thrive was a common symptom. Progression of skin to systemic involvement was seen in 27.9%. In 76.7%, skin lesions cleared over a period of 2 to 4 years. Complete remission was seen in 56.9% of children over a period of 3 to 7 years, while 8.1% children died of complicationsand 31.8% were lost to follow-up.

CONCLUSIONS

Long-term follow-up in this study has shown cutaneous LCH without systemic involvement has a good prognosis. Skin involvement,along with failure to thrive, was the most common clinical presentation in our study. The skeletal system was the second most common organ system involved.

Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is caused by clonal expansion of myeloid precursors that differentiate into CD1a+/CD207+ cells in lesions that leads to a spectrum of organ involvement and dysfunction. The pathogenic cells are defined by constitutive activation of the MAPK signaling pathway. Treatment of LCH is risk-adapted: patients with single lesions may respond well to local treatment, whereas patients with multisystem disease require systemic therapy. Although survival rates for patients without organ dysfunction is excellent, mortality rates for patients with organ dysfunction may reach 20%. Despite progress made in the treatment of LCH, disease reactivation rates remain above 30%, and standard second-line treatment is yet to be established. Treatment failure is associated with increased risks for death and long-term morbidity, including LCH-associated neurodegeneration. Early case series report promising clinical responses in patients with relapsed and refractory LCH treated with BRAF or MEK inhibitors, although potential for this strategy to achieve cure remains uncertain.

Chest computed tomography findings for a cohort of children with pulmonary Langerhans cell histiocytosis

OBJECTIVE

This study was undertaken to describe the spectrum of lung computed-tomography (CT) findings in children with pulmonary Langerhans cell histiocytosis (PLCH) and to evaluate for this population the CT-scan nodule and cyst scores proposed by adult pulmonologists at diagnosis and during follow-up.

METHODS

Among 175 children with PLCH identified in the French national population-based Langerhans cell histiocytosis cohort, 60 were retrospectively selected by the availability of CT for a central review by three pediatric radiologists. These 60 patients are representative of childhood PLCH for almost all clinical aspects, except a lower percentage of risk organ involvement (38% vs 54%; P = 0.05).

RESULTS

The 60 children's chest CT scans (n = 218) were reviewed. At diagnosis, 63% of them had nodules, 53% had cysts, and 29% had both. The percentages of patients with nodules or cysts increased from diagnosis to peak disease activity, respectively, from 63% to 73% and from 53% to 66%. The costophrenic angle was involved in 71%. Patients with pneumothorax (25%) had a higher median cyst score. Alveolar consolidation was observed in 34%. Patients with low CT-scan nodule and cyst scores had no long-term pulmonary sequelae.

CONCLUSIONS

Well-known characteristics of adult PLCH (nodules and cysts) were observed in children. The chest CT scores proposed by adult pulmonologists could easily be applied to childhood PLCH. Lesions in children, unlike those in adults, are frequently located near the costophrenic angles. Alveolar consolidation might be considered an atypical feature of childhood PLCH.

Childhood Langerhans cell histiocytosis with severe lung involvement: a nationwide cohort study

BACKGROUND

Lung involvement in childhood Langerhans cell histiocytosis (LCH) is infrequent and rarely life threatening, but occasionally, severe presentations are observed.

METHODS

Among 1482 children (< 15 years) registered in the French LCH registry (1994-2018), 111 (7.4%) had lung involvement. This retrospective study included data for 17 (1.1%) patients that required one or more intensive care unit (ICU) admissions for respiratory failure.

RESULTS

The median age was 1.3 years at the first ICU hospitalization. Of the 17 patients, 14 presented with lung involvement at the LCH diagnosis, and 7 patients (41%) had concomitant involvement of risk-organ (hematologic, spleen, or liver). Thirty-five ICU hospitalizations were analysed. Among these, 22 (63%) were secondary to a pneumothorax, 5 (14%) were associated with important cystic lesions without pneumothorax, and 8 (23%) included a diffuse micronodular lung infiltration in the context of multisystem disease. First-line vinblastine-corticosteroid combination therapy was administered to 16 patients; 12 patients required a second-line therapy (cladribine: n = 7; etoposide-aracytine: n = 3; targeted therapy n = 2). A total of 6 children (35%) died (repeated pneumothorax: n = 3; diffuse micronodular lung infiltration in the context of multisystem disease: n = 2; following lung transplantation: n = 1). For survivors, the median follow-up after ICU was 11.2 years. Among these, 9 patients remain asymptomatic despite abnormal chest imaging.

CONCLUSIONS

Severe lung involvement is unusual in childhood LCH, but it is associated with high mortality. Treatment guidelines should be improved for this group of patients: viral infection prophylaxis and early administration of a new LCH therapy, such as targeted therapy.

Congenital Langerhans cell histiocytosis

Langerhans cell histiocytosis is a rare pathology with different clinical manifestations in the neonatal period ranging from isolated bone lesions to systemic compromise. We report a case of Langerhans cell histiocytosis including a literature review focused on the clinical manifestations, diagnosis, and treatment. A one-month-old patient was brought to medical consultation with lymphadenopathy and skin lesions, which were initially managed as an infectious pathology. The disease continued its progression without improvement with the treatment until the patient died due to respiratory failure. The lymph node and skin biopsies revealed infiltration of atypical cells with positive immunohistochemistry for S100, CD1, and CD68 confirming Langerhans cell histiocytosis. This disorder represents a great challenge and, therefore, it is important to alert and sensitize medical teams about it for timely diagnosis and management.

Management of severe pulmonary Langerhans cell histiocytosis in children

Patients with pulmonary Langerhans cell histiocytosis (LCH) typically have a benign course but may have extensive cystic lung disease with rare life-threatening complications including multiple and recurrent pneumothoraces and respiratory failure. We report seven severely affected pediatric patients treated with chemotherapy, aggressive chest tube management, and pleurodesis of whom five survived. Patients with extraordinary amounts of pulmonary cystic disease and multiple pneumothoraces due to LCH can have remarkable, curative outcomes with early recognition, optimal LCH-directed therapy, and supportive care.

Paediatric pulmonary Langerhans cell histiocytosis

Paediatric pulmonary Langerhans cell histiocytosis (pPLCH) is a rare diffuse cystic lung disease. Unlike pulmonary Langerhans cell histiocytosis (LCH) in adults, which is often seen as an isolated condition with smoking being a major risk factor, isolated pPLCH is vanishingly rare in children and it is most often a component of multisystem LCH. Diagnosis should be based on histological and immunophenotypic examination of affected tissue in addition to clinical and radiological features. It should be considered an important differential for diffuse cystic lung disease in paediatric patients. Recent progress in the biological understanding of the disease supports the classification of LCH as an inflammatory myeloid neoplasia. Chemotherapy and specific management of respiratory complications are the mainstays of treatment. The lungs are no longer considered a "risk organ" in LCH as pulmonary involvement is not associated with a worse prognosis than the involvement of other organs. Multidisciplinary treatment approaches are needed. Prognosis can be good but is adversely influenced by multisystem involvement, and complications such as pneumothoraces and respiratory failure can be life threatening. This review aims to give an overview of this condition, with a focus on the diagnosis, monitoring and management of complications such as pneumothoraces and respiratory failure, which can be challenging for the paediatric respiratory specialist.

EDUCATIONAL AIMS

To give an overview of paediatric pulmonary LCH.To discuss the differential diagnosis of paediatric cystic lung disease.

BRAF V600E Mutation: A Significant Biomarker for Prediction of Disease Relapse in Pediatric Langerhans Cell Histiocytosis

Langerhans cell histiocytosis (LCH) is a rare disease presenting with usually a localized disease but sometimes a widespread aggressive disorder especially in children. Among the somatic mutations in RAF-MEK-ERK pathway, especially BRAF mutation has been detected so far in LCH. We aimed in this study to investigate the prognostic significance of the mutations of target genes playing a role in the RAF-MEK-ERK pathway in pediatric LCH. Mutation analyses were performed on tumor DNA extracted from formalin-fixed paraffin-embedded biopsy specimens of 38 pediatric LCH cases using a direct sequencing technique for BRAF, ARAF, MAP2K1, and MAP3K1 genes. The mutational status was correlated statistically with survival, clinical progression (disease relapse), and the established clinical prognostic parameters of LCH such as age, gender, localization, multisystem disease, central nervous system risk lesions, and risk organ or special-site involvement. BRAF V600E mutation was detected in 14 cases (36.8%), whereas ARAF mutation was found in only 1 case. No mutations were identified for MAP2K1 and MAP3K1 genes. The association of BRAF V600E mutation was significant in children with multisystem disease, younger age (<2 years), skin, and special organ involvement. BRAF V600E mutation was an independent predictive parameter for disease relapse. We therefore conclude that BRAF V600E mutation may be a significant marker for predicting disease progression in LCH and a candidate for targeted therapy for children with disease relapse and multisystem disease.

Bilateral Pulmonary Langerhans's Cell Histiocytosis is Surgical Challenge in Children: A Case Report

Background  Pulmonary Langerhans's cell histiocytosis (PLCH) is a rare cause of interstitial lung disease in children and more than half of the cases are bilateral. Persistent respiratory distress due to spontaneous pneumothorax (SP) in bilateral PLCH may refractory to conservative treatment and posed a great challenge to surgical modalities. A 3-year-old boy with SP due to bilateral PLCH is presented to discuss the surgical options of recurrent and refractory PLCH cases in children.

Case Report  The patient was admitted to the emergency department with severe respiratory distress and SP. After chest tube insertion, biopsy from neck mass revealed Langerhans's cell histiocytosis. Chemotherapy including vinblastine and prednisone was initiated. Due to persistent respiratory difficulty and air leaks, talc pleurodesis and thoracoscopic bullae excision with pleural decortication were performed. Two months after the admission, due to nosocomial infection and severe respiratory distress, extracorporeal membranous oxygenation (ECMO) support was initiated. The patient was died of ECMO complications on 24th day of ECMO.

Conclusion  Despite the use of chemotherapy and surgical excision of cystic lesions, bilateral PLCH in children may have lethal outcome. Other treatment options including respiratory support with ECMO and lung transplantation should be considered as last resort of treatment alternative in persistent cases.

Childhood pulmonary Langerhans cell histiocytosis: a comprehensive clinical-histopathological and BRAFV600E mutation study from the French national cohort

Childhood pulmonary Langerhans cell histiocytosis (PLCH) is a rare disease. Its pulmonary histopathology, according to comprehensive clinical-radiological findings and BRAF^V600E mutation status, has not yet been thoroughly documented. From the 167 childhood PLCH cases entered in the French National Histiocytosis Registry (1983-2016), we retrieved lung biopsies from a consecutive retrospective series of 17 patients, diagnosed when they were 2 weeks to 16 years old (median, 9.4 years), and report the clinical and histopathological findings herein. Histological analyses of biopsies (16 surgical and 1 postmortem) found the following features, alone or associated: Langerhans cell (LC) nodules with cavitation (9/17), cysts (14/17), fibrotic scars (2/17), peribronchiolar topographic distribution of the lesions (10/17), and accessory changes, like stretch emphysema (7/17). Those characteristics closely resemble those describing adult PLCH. However, unusual findings observed were 2 large nodules and a diffuse interstitial LC infiltrate. BRAF^V600E mutation was detected in 4 of 12 samples tested, notably in the 3 with unusual features. In conclusion, childhood PLCH mostly shares the common histology features already described in adult PLCH, regardless of age. Because smoking is considered the major trigger in PLCH pathogenesis, the findings based on this series suggest other inducers of bronchiolar LC recruitment, especially in very young patients.

Successful management of isolated pulmonary Langerhans cell histiocytosis in a 50-year-old man with early diagnosis using transbronchial cryobiopsy: A case report

RATIONALE

Isolated pulmonary Langerhans cell histiocytosis (PLCH) is rare in adults. The gold standard diagnosis requires surgical lung biopsy. However, few cases have been diagnosed with transbronchial cryobiopsy (TBCB) sampling in the early stages of the disease, particularly in China.

PRESENTING CONCERNS

A 50-year-old man was referred for dry cough and exertional dyspnea of more than 1 week. High-resolution computed tomography (HRCT) of the chest revealed symmetric nodules and cyst lesions with upper lobe infiltrate. Further history taking indicated that he had smoked 20 cigarettes per day for more than 30 years. Therefore, PLCH was highly suspected. However, he refused surgical lung biopsy, and TBCB was attempted to complete diagnosis.

DIAGNOSIS

Emission computed tomography excluded the possibility of extrapulmonary involvements, and pathological findings supported the diagnosis of isolated PLCH.

INTERVENTIONS

Smoking cessation and prednisone treatment were used for patient management.

OUTCOMES

The symptoms receded with significant improvement of chest HRCT during 2-months of follow-up.

LESSONS

Early diagnosis contributes to the prognosis of isolated PLCH in adults, and TBCB may be an alternative to conventional surgical lung biopsy for pathological diagnosis of PLCH.

Clinical Research of Pulmonary Langerhans Cell Histiocytosis in Children

Background:

Pulmonary Langerhans cell histiocytosis (PLCH) is an interstitial primary pulmonary disease, characterized by Langerhans cell proliferation. It is easily misdiagnosed in children. This study aimed to characterize the clinical manifestations and features of PLCH by retrospective analysis.

Methods:

A retrospective analysis was performed in 117 PLCH patients out of 338 LCH patients who were admitted in our center from November 2006 to October 2013. Variables between two groups were compared by Mann-Whitney U-test and Chi-square test. Kaplan-Meier curves were constructed to compare the survival rates and Cox regression to evaluate the effect of risk factors.

Results:

The median age of PLCH group was significantly lower than that of non-PLCH group (18.63 months vs. 43.4 months, P < 0.001). All PLCH children had other organ involvement and only 11 cases (9.4%) had respiratory symptoms. The most common radiologic finding was cystic lesions (29 cases, 24.8%). Pulmonary function abnormalities were dominated by obstructive ventilatory dysfunction (63 cases, 82.9%). The 5-year overall survival (OS) of PLCH children was 93.6% ± 2.3% and the event-free survival (EFS) was 55.7% ± 5.2%. Among the 38 cases with progressed or relapsed disease, five cases (13.2%) were due to progression or recurrence of lung damage. The 5-year OS of PLCH children with “risk organ” involvement was significantly lower than those without “risk organ” involvement (86.0% ± 4.9% vs. 100%, χ² = 8.793, P = 0.003). The difference of EFS between two groups was also significant (43.7% ± 7.7% vs. 66.3% ± 6.5%, χ² = 5.399, P = 0.020). The “risk organ” involvement had a significant impact on survival (hazard ratio = 1.9, P = 0.039).

Conclusions:

PLCH mainly occurs in young children, and only a small percentage of patients have respiratory symptoms. They generally have other organ involvement. Most of PLCH children have a good prognosis and most lung lesions could have improved or stabilized. Management of “risk organ” involvement is the key point to improving EFS.

Langerhans cell histiocytosis in children: History, classification, pathobiology, clinical manifestations, and prognosis

Langerhans cell histiocytosis (LCH) is an inflammatory neoplasia of myeloid precursor cells driven by mutations in the mitogen-activated protein kinase pathway. When disease involves the skin, LCH most commonly presents as a seborrheic dermatitis or eczematous eruption on the scalp and trunk. Evaluation for involvement of other organ systems is essential, because 9 of 10 patients presenting with cutaneous disease also have multisystem involvement. Clinical manifestations range from isolated disease with spontaneous resolution to life-threatening multisystem disease. Prognosis depends on involvement of risk organs (liver, spleen, and bone marrow) at diagnosis, particularly on presence of organ dysfunction, and response to initial therapy. Systemic treatment incorporating steroids and cytostatic drugs for at least one year has improved prognosis of multisystem LCH and represents the current standard of care.

Merkel cell polyomavirus and Langerhans cell neoplasm

BACKGROUND

The relationship between various external agents such as pollen, food, and infectious agents and human sensitivity exists and is variable depending upon individual's health conditions. For example, we believe that the pathogenetic potential of the Merkel cell polyomavirus (MCPyV), the resident virus in skin, is variable and depends from the degree of individual's reactivity. MCPyV as well as Epstein-Barr virus, which are normally connected with humans under the form of subclinical infection, are thought to be involved at various degrees in several neoplastic and inflammatory diseases. In this review, we cover two types of Langerhans cell neoplasms, the Langerhans cell sarcoma (LCS) and Langerhans cell histiocytosis (LCH), represented as either neoplastic or inflammatory diseases caused by MCPyV.

METHODS

We meta-analyzed both our previous analyses, composed of quantitative PCR for MCPyV-DNA, proteomics, immunohistochemistry which construct IL-17 endocrine model and interleukin-1 (IL-1) activation loop model, and other groups' data.

RESULTS

We have shown that there were subgroups associated with the MCPyV as a causal agent in these two different neoplasms. Comparatively, LCS, distinct from the LCH, is a neoplastic lesion (or sarcoma) without presence of inflammatory granuloma frequently observed in the elderly. LCH is a proliferative disease of Langerhans-like abnormal cells which carry mutations of genes involved in the RAS/MAPK signaling pathway. We found that MCPyV may be involved in the development of LCH.

CONCLUSION

We hypothesized that a subgroup of LCS developed according the same mechanism involved in Merkel cell carcinoma pathogenesis. We proposed LCH developed from an inflammatory process that was sustained due to gene mutations. We hypothesized that MCPyV infection triggered an IL-1 activation loop that lies beneath the pathogenesis of LCH and propose a new triple-factor model.

Langerhans cell histiocytosis in children - a disease with many faces. Recent advances in pathogenesis, diagnostic examinations and treatment

Langerhans cell histiocytosis is a rare clonal disease characterized by the proliferation of CD1a-positive immature dendritic cells. The purpose of this article was to present an updated review of recent advances in the pathogenesis, clinical features, imaging and treatment of this disease. The discovery of oncogenic BRAF mutations and the presence of proinflammatory cytokines and chemokines confirmed the unusual characteristics of this disease. Currently, children with organ involvement who do not have a good response to chemotherapy and have neurodegeneration or diabetes insipidus are the most problematic patients. Further research is needed to improve the results of treatment.

Treatment Outcome of Children With Multisystem Langerhans Cell Histiocytosis: The Experience of a Single Children's Hospital in Shanghai, China

We reported the outcome of 150 children newly diagnosed with multisystem langerhans cell histiocytosis following a langerhans cell histiocytosis-II-based protocol (arm B). However, the continuation treatment was extended to 56 weeks and etoposide was omitted from the continuation treatment. Risk organ (RO) involvement was defined as: liver (≥3 cm with or without functional impairment); spleen (≥2 cm below the costal margin in the midclavicular line); hematopoietic system (hemoglobin <100 g/L, and/or white blood cell count <4.0×10/L, and/or platelets <100×10/L). The lungs are not considered a RO in the current study. For the 59 patients with RO involvement (RO+), the rapid response rate (week 6) was 61.0% and the 3-year overall survival 73.4%±5.9%. Rapid responders had a better 3-year survival rate than poor responders (90.9%±5.0% vs. 45.7%±11.0%, P<0.001). Ninety-one patients without RO involvement (RO-) had a relatively low 3-year cumulative reactivation rate (10.7%). No deaths occurred in this subgroup and the 3-year overall survival of RO- patients was 100%. Poor responders of RO+ patients had an extremely poor prognosis. An effective salvage therapy is essential for this high-risk group. The initial treatment intensity and duration of continuation therapy both impact disease reactivation in RO- patients.

Perianal Langerhans cell histiocytosis: a rare presentation in an adult male

Langerhans cell histiocytosis (LCH) is a rare disease characterized by a proliferation of cells that show immunophenotypic and ultrastructural similarities with antigen-presenting Langerhans cells of mucosal sites and skin. LCH in adults is rare, and there are still many undiagnosed/misdiagnosed patients. We describe LCH involvement of the perianal region of a 33-year-old male with a previous history of diabetes insipidus. The differential diagnosis and all the reported cases of LCH of the perianal skin involvement since its description in 1984 till 2016 are discussed. LCH should be considered in the differential diagnosis of perianal ulceration, especially in young patients where topical drug treatment has failed. The history of previous central diabetes insipidus of unknown etiology demands imaging studies in order to rule out central involvement of the disease.

Inflammatory serum cytokines and chemokines increase associated with the disease extent in pediatric Langerhans cell histiocytosis

OBJECTIVE

Langerhans cell histiocytosis (LCH) is characterized by immature dendritic cell proliferation, infiltration of LCH lesions by various inflammatory cells, and a lesional cytokine storm. It is classified into three groups on the basis of disease extent, namely, multisystem with risk-organ involvement (MS+), multisystem without risk-organ involvement (MS-), and single-system (SS) disease. We comprehensively analyzed whether serum levels of cytokines/chemokines reflect the disease extent.

METHODS

Serum samples from 52 children with LCH (eight, 25, and 19 with MS+, MS-, and SS, respectively) and 34 control children were analyzed quantitatively for 48 humoral factors. DNA samples extracted from biopsied LCH lesions from 12 patients were tested for BRAF V600E status.

RESULTS

The LCH patients had significantly higher serum levels of IL-1Ra, IL-3, IL-6, IL-8, IL-9, IL-10, IL12, IL-13, IL-15, IL-17, IL-18, TNF-α, G-CSF, M-CSF, MIF, HGF, VEGF, CCL2, CCL3, CCL7, CXCL1, and CXCL9 than the controls by univariate analysis. Of these IL-9, IL-15 and MIF were significant by multivariate analysis; but not differed between MS and SS diseases. MS disease associated with significantly higher IL-2R, IL-3, IL-8, IL-18, M-CSF, HGF, CCL2, CXCL1, and CXCL9 levels than SS disease by univariate analysis. Of these, CCL2 and M-CSF were significant by multivariate analysis. IL-18 levels were significantly higher in MS+ disease than MS- disease. The LCH patients with BRAF V600E mutation had higher serum levels of CCL7.

CONCLUSION

Numerous inflammatory cytokines and chemokines play a role in LCH. Of those, more specific ones reflect the disease extent (MS vs. SS and MS+ vs. MS-) or the BRAF V600E mutation status. It is thought that the most responsible cytokines and chemokines involved in the poor outcome may become future candidate therapeutic targets in LCH.

[Clinical features and prognosis of Langerhans cell histiocytosis in children: an analysis of 34 cases]

OBJECTIVE

To investigate the clinical features and prognosis of children with Langerhans cell histiocytosis (LCH).

METHODS

A retrospective analysis was performed for the clinical data of 34 children with newly diagnosed LCH.

RESULTS

The 34 children had a median age of 14.5 months (range: 22 d to 60 months). Of all 34 children, 23 were aged 0-2 years and 11 were aged >2 years. There were 17 children in the high-risk group and 17 in the low-risk group. Thirty children received chemotherapy, and the 6-week and 12-month overall response rates were 67% (20/30) and 87% (26/30), respectively. The 3-year overall survival (OS) rate was 86%±6% and the 3-year event-free survival (EFS) rate was 64%±9%. Compared with the low-risk group, the high-risk group had significantly lower 6-week chemotherapy response rate (47% vs 87%; P<0.05), 3-year OS rate (72%±12% vs 100%; P<0.05), and 3-year EFS rate (46%±13% vs 82%±9%; P<0.05). There was no significant difference in the 12-month chemotherapy response rate between the high-risk and low-risk groups (80% vs 93; P>0.05). The high-risk group had a recurrence rate of 27% and a mortality rate of 27%. There were no recurrence or deaths in the low-risk group.

CONCLUSIONS

Children with LCH have a high overall survival rate, but the high-risk patient has a low 6-week response rate of induction chemotherapy and poor long-term prognosis.

Langerhans Cell Histiocytosis and Langerhans Cell Sarcoma: Current Understanding and Differential Diagnosis

Langerhans cell (LC) histiocytosis (LCH) and LC sarcoma (LCS) are proliferative processes consisting of cells having morphologic and phenotypic features of Langerhans cells (LCs), although the latter may have lost some of these features. Because neoplastic nature of LCH as well as LCS is more likely by recent studies, a category of LC hyperplasia can be better characterized. LCH and LCS are rarely seen in daily pathology practice, but it is important to accurately characterize these lesions. For this purpose, an outline covering proliferations of LC and related cells was constructed. The scheme of this outline is based especially on evaluating borderline lesions, neoplastic trans-differentiation, and degree of similarity with the normal counter-parts. In addition, the organization and update of the current classification scheme for histiocytic and dendritic-cell proliferations is presented.

Clinical Characteristics and Treatment of Langerhans Cell Histiocytosis

Langerhans cell histiocytosis (LCH) is a disease caused by clonal proliferation of CD1a+/CD207+ cells that is characterized by a spectrum of varying degrees of organ involvement and dysfunction. Treatment of LCH is risk adapted; patients with single lesions may respond well to local treatment, whereas patients with multi-system disease and risk-organ involvement require more intensive therapy. Although survival for patients without organ dysfunction is excellent, mortality rates for patients with organ dysfunction may reach 30% to 40%. For patients with low-risk disease, although cure is almost universal, disease reactivation rates are in excess of 30%.

Acute-phase ITIH4 levels distinguish multi-system from single-system Langerhans cell histiocytosis via plasma peptidomics

BACKGROUND

Langerhans cell histiocytosis (LCH) is a proliferative disorder in which abnormal Langerhans cell (LC)-like cells (LCH cells) intermingle with inflammatory cells. Whether LCH is reactive or neoplastic remains a controversial matter. We recently described Merkel cell polyomavirus (MCPyV) as a possible causative agent of LCH and proposed interleukin-1 loop model: LCH is a reactive disorder with an underlying oncogenic potential and we now propose to test this theory by looking for acute markers of inflammation. We detected MCPyV-DNA in the peripheral blood cells of patients with high-risk organ-type (LCH-risk organ (RO) (+)) but not those with non-high-risk organ-type LCH (LCH-RO (-)); this difference was significant. LCH-RO (-) is further classified by its involvement of either a single organ system (SS-LCH) or multiple organ systems (MS-LCH). In patients with LCH-RO (-), MCPyV-DNA sequences were present in LCH tissues, and significant differences were observed between LCH tissues and control tissues associated with conditions such as dermatopathic lymphadenopathy and reactive lymphoid hyperplasia. Although MCPyV causes subclinical infection in nearly all people and 22 % of healthy adults will harbor MCPyV in their buffy coats, circulating monocytes could serve as MCPyV reservoirs and cause disseminated skin lesions.

METHODS

Plasma sample from 12 patients with LCH-RO (-) (5 MS-LCH and 7 SS-LCH) and 5 non-LCH patients were analyzed by peptidomics. Mass spectrometry (MS) spectra were acquired and peptides exhibiting quantitative differences between MS-LCH and SS-LCH patients were targeted.

RESULTS

One new candidate biomarker, m/z 3145 was selected and identified after obtaining a MS/MS fragmentation pattern using liquid chromatography-MS/MS. This peak was identified as a proteolytic fragment derived from inter-alpha-trypsin inhibitor heavy chain 4 (ITIH4, [PDB: Q14624]).

CONCLUSIONS

Peptidomics of LCH have revealed that the level of acute-phase ITIH4 distinguishes MS-LCH-RO (-) from SS-LCH-RO (-). Acute-phase proteins serve non-specific, physiological immune functions within the innate immune system. LCH may be a reactive disorder with both underlying neoplastic potential of antigen presenting cells harboring BRAF mutations and hyper-immunity of other inflammatory cells against MCPyV infection. Among LCH-RO (-), MCPyV-DNA sequences were present in both MS-LCH tissues and SS-LCH tissues without significant differences. ITIH4 may show that LCH activity or LCH subtypes correlates with the systemic or localized reactions of MCPyV infection.

[Pulmonary manifestations of Langerhans cell histiocytosis]

Pulmonary Langerhans cell histiocytosis is a rare diffuse cystic interstitial pneumonia of unknown etiology that occurs selectively in young smokers of both genders. The multicenter studies conducted by the reference center have better defined the short and medium terms natural history of the disease and the clinical management of patients. A substantial proportion of patients experience a dramatic decline in their lung function soon after diagnosis. Importantly, smoking cessation is associated with a decreased risk of subsequent deterioration. Cladribine, a purine analogue, chemotherapy may dramatically improve lung function in patients with progressive pulmonary Langerhans cell histiocytosis, but this treatment should be used only in the setting of clinical research. Specific pulmonary hypertension therapies (anti-endothelin receptors, inhibitors of phosphodiesterases) may be used with caution in specialized centres for patients with severe pulmonary hypertension, and seem to be well tolerated. The recent identification of the V600E mutation of the BRAF oncogene in approximately half of the Langerhans cell histiocytosis lesions, including pulmonary granulomas, represents an important step forward in the understanding of the pathogenesis of Langerhans cell histiocytosis. Potentially it opens the way to targeted therapies.

Interleukin-1 loop model for pathogenesis of Langerhans cell histiocytosis

We propose Langerhans cell histiocytosis (LCH) is an inflammatory process that is prolonged by mutations. We hypothesize that Merkel cell polyomavirus (MCPyV) infection triggers an interleukin-1 (IL-1) activation loop that underlies the pathogenesis of LCH. Langerhans cells (LCs) are antigen presenting cells in the skin. When LCs encounter exogenous antigens, they migrate from the epidermis into draining lymphoid tissues to initiate T-cell activity. It has been proposed that LC migration-related factors, including E-cadherin, matrix metalloproteinase, and Notch ligand induce LCH activity. We found that the tyrosine phosphatase SHP-1, which binds IL-1 receptor-associated kinase 1, is expressed at a significantly higher level in LCH affecting multiple organ systems (MS-LCH) than in LCH affecting a single organ system (SS-LCH). IL-1 stimulates T helper 17 cells and their signature cytokine IL-17 had been a matter of controversy. We detected higher levels of IL-17A receptor expression in MS-LCH than in SS-LCH and proposed an IL-17 endocrine model that could settle the controversy. IL-1 is the first cytokine secreted in response to sensitizers and promotes LC migration from sentinel tissues. Myeloid differentiation primary response 88 (MyD88), downstream of the IL-1 receptor, has functions in both RAS signaling and inflammation, leading to human cell transformation. In 2010, an activating mutation in the B-rapidly accelerated fibrosarcoma gene (BRAF) V600E was found in LCH. This BRAF mutation induces phosphorylation of the extracellular signal-regulated kinase (ERK) that may play an important role with MyD88 in LCH pathogenesis. However, phosphorylated ERK (pERK) is rapidly dephosphorylated by dual specificity phosphatase 6 (DUSP6), and limited proliferation is predicted in BRAF mutant cells. MyD88 binds pERK via its D-domain, thereby preventing pERK-DUSP6 interaction and maintaining ERK in an active, phosphorylated state. We detected MCPyV-DNA in the peripheral blood cells of two out of three patients with LCH in high-risk organs but not in those of patients with LCH in non-high-risk organs (0/12; P = .029). MCPyV infection can trigger precursor LCH cells with BRAF mutation to produce IL-1; the IL-1 loop is amplified in all LCH subclasses. Our model indicates both BRAF mutation and IL-1 loop regulation as potential therapeutic targets.

Outcomes of children younger than 24 months with langerhans cell histiocytosis and bone involvement: a report from a single institution

BACKGROUND

Langerhans cell histiocytosis (LCH) is a rare disorder that ranges from single-system to disseminated multisystem disease. Patients younger than 24 months of age more commonly present with risk organ (liver, spleen, hematopoietic system, or lung) involvement at diagnosis and have a poor prognosis. Treatment approaches have changed over the last 25 years. Our goal was to describe the course and outcomes of patients younger than 24 months of age at diagnosis and identify the role of bone involvement in outcomes.

METHODS

We conducted a retrospective chart review of patients diagnosed with LCH at Children's Hospital Los Angeles from 1984 to 2010, focusing on 71 patients younger than 24 months of age at diagnosis.

RESULTS

Ten patients had single bone lesions at diagnosis and did well irrespective of therapy. The majority of patients (40/71 or 56%) had multiple bone lesions. Of the 37 patients with multisystem disease, 27 children (73%) had risk organ involvement. Fourteen patients with risk organ involvement received ≤ 6 months of initial chemotherapy with prednisone and vinblastine. Six of these patients had reactivation of the disease, and bone was the most frequent site of reactivation. Seven patients with risk organ involvement were treated with at least 12 months of chemotherapy. Only one of these patients had reactivation of the disease, and none died. The majority (7/10) of patients with risk organ involvement who progressed on therapy died despite multiple treatment regimens.

CONCLUSIONS

Patients younger than 24 months of age at diagnosis are more likely to have multiple bone lesions than older patients, supporting that a radiographic skeletal survey at the time of LCH diagnosis is important to evaluate the extent of bone involvement. Bones were the most common site for reactivation for all patients. As expected, subjects with risk organ involvement had better outcomes when treated with systemic chemotherapy for at least 1 year.

LEVEL OF EVIDENCE

As a retrospective review of all cases at our institution over a 26-year period, this article represents level IV evidence.

Differentiating skin-limited and multisystem Langerhans cell histiocytosis

OBJECTIVE

To identify features associated with multisystem involvement and therapeutic failure in patients with skin Langerhans cell histiocytosis (LCH).

STUDY DESIGN

We reviewed medical records of 71 consecutive patients with LCH with skin involvement evaluated at Texas Children's Hospital and analyzed clinical features, laboratory results, and the presence of circulating cells with the BRAF-V600E mutation with respect to initial staging and clinical outcomes.

RESULTS

Skin disease in patients older than 18 months of age at diagnosis was associated with the presence of multisystem disease (OR, 9.65; 95% CI, 1.17-79.4). Forty percent of patients referred for presumed skin-limited LCH had underlying multisystem involvement, one-half of these with risk-organ involvement. Patients with skin-limited LCH had a 3-year progression-free survival of 89% after initial therapy, and none developed multisystem disease. Patients with skin/multisystem involvement had a 3-year progression-free survival of 44% with vinblastine/prednisone therapy, and risk-organ involvement did not correlate with failure to achieve nonactive disease. Circulating cells with BRAF-V600E were detected at higher frequency in patients with multisystem involvement (8 of 11 skin/multisystem vs 1 of 13 skin-limited; P = .002).

CONCLUSION

Skin-limited LCH necessitates infrequent therapeutic intervention and has a lower risk of progression relative to skin plus multisystem LCH. The less-aggressive clinical course and lack of circulating cells with the BRAF-V600E mutation in skin-limited LCH suggest a different mechanism of disease origin compared with multisystem or risk-organ disease.

Recent advances in Langerhans cell histiocytosis

The purpose of this review is to provide an updated overview of the pathogenesis and treatment of Langerhans cell histiocytosis (LCH). The pathogenesis of LCH remains obscure and the optimal treatment for LCH has not been established, although incremental progress has been made. Proinflammatory cytokines and chemokines are known to play a role in LCH, which suggests that LCH is an immune disorder. However, the oncogenic BRAF mutation is also detected in more than half of LCH patients, which suggests that LCH is a neoplastic disorder. Remaining major issues in the treatment of LCH are how to rescue patients who have risk-organ involvement but do not respond to first-line therapy, the optimal treatment for the orphan disease of multifocal adult LCH, and how to reduce and treat central nervous system-related consequences, such as central diabetes insipidus and neurodegeneration. More research is needed to better understand the pathogenesis of this disease and to resolve the treatment issues.

Clofarabine salvage therapy in refractory multifocal histiocytic disorders, including Langerhans cell histiocytosis, juvenile xanthogranuloma and Rosai-Dorfman disease

BACKGROUND

Existing therapies for recurrent or refractory histiocytoses, including Langerhans cell histiocytosis (LCH), juvenile xanthogranuloma (JXG), and Rosai-Dorfman disease (RDD), have limited effectiveness. We report our experience with using clofarabine as therapy in children with recurrent or refractory histiocytic disorders, including LCH (11 patients), systemic JXG (4 patients), and RDD (3 patients).

METHODS

Patients treated with clofarabine for LCH, JXG, or RDD by Texas Children's Hospital physicians or collaborators between May 2011 and January 2013 were reviewed for response and toxicity.

RESULTS

Patients were treated with a median of three chemotherapeutic regimens prior to clofarabine. Clofarabine was typically administered at 25 mg/m(2) /day for 5 days. Cycles were administered every 28 days for a median of six cycles (range: 2-8 cycles). Seventeen of 18 patients are alive. All surviving patients showed demonstrable improvement after two to four cycles of therapy, with 11 (61%) complete responses, 4 (22%) partial responses, and 2 patients still receiving therapy. Five patients experienced disease recurrence, but three of these subsequently achieved complete remission. All patients with JXG and RDD had complete or partial response at conclusion of therapy. Side effects included neutropenia in all patients. Recurring but sporadic toxicities included prolonged neutropenia, severe vomiting, and bacterial infections.

CONCLUSION

Clofarabine has activity against LCH, JXG, and RDD in heavily pretreated patients, but prospective multi-center trials are warranted to determine long-term efficacy, optimal dosing, and late toxicity of clofarabine in this population.