Incidence of Langerhans cell histiocytosis in children: a population-based study

Langerhans cell histiocytosis of the orbit: pediatric case series

OBJECTIVE

To describe the clinical, imaging characteristics, and treatment of pediatric orbital Langerhans cell histiocytosis (LCH).

DESIGN

Retrospective case series.

PARTICIPANTS

Children with orbital LCH.

METHODS

Children with orbital LCH who presented to 4 different centres over the past 10 years. Demographic details, presenting features, imaging, histopathology, immunohistochemistry, and management outcomes were analyzed.

RESULTS

Sixteen patients were reviewed. The mean age of presentation was 6.56 ± 4.38 years (range, 1-18 years). Eyelid swelling was the most common presenting feature (13, 81%), followed by proptosis (1, 5%), eyebrow swelling (1,5%), and temple swelling (1, 5%). Imaging revealed superior orbital lesions with osteolytic defects of the orbital roof in 13 (72.2%) patients. Frontal and zygomatic bones were the most commonly affected. All the orbital lesions were extraconal. All patients in the study were diagnosed with LCH from orbital tissue biopsy. Three patients also demonstrated extra-orbital involvement. Two patients (12.5%) had intraoperative steroid injection with curettage, and 1 patient (6.25%) underwent curettage only. The remainder of the patients (n = 13, 81.25%) received systemic steroids and chemotherapy after undergoing biopsy. All patients had complete remission of disease without any signs of recurrence, except for 1 case of refractory LCH.

CONCLUSIONS

LCH is a rare disorder of the orbit and should be considered in the differential diagnosis for osteolytic lesions involving the superior orbit among the pediatric age group. Histopathologic confirmation is mandatory. Although optimal treatment remains controversial, complete removal of unifocal orbital LCH is recommended and may be achieved through excision and curettage.

Osteosarcoma and Langerhans Cell Histiocytosis in a Pediatric Patient with Lynch Syndrome: A Case Report

CASE

Lynch syndrome (hereditary nonpolyposis colorectal cancer) is associated with extracolonic manifestations, but skeletal tumors are rare. Our patient, a 12-year-old boy with Lynch syndrome, developed osteosarcoma of the left femur. Treatment included cytotoxic chemotherapy, wide resection, and pembrolizumab. Two years later, he developed an aggressive lesion in the contralateral femur that was thought to be metastatic osteosarcoma but which histology revealed to be Langerhans cell histiocytosis.

CONCLUSION

This case underscores the importance of advanced testing in patients with osteosarcoma and poor response to chemotherapy, and of tissue sampling when patients with a primary malignancy develop new bone lesions.

LEVEL OF EVIDENCE

IV.

Hematolymphoid neoplasm mimicking endodontic lesions: case series and review of the literature

Hematolymphoid neoplasms originating in the periapical region of a tooth are rare occurrences. Their signs, symptoms, and radiographic findings can also mimic lesions of endodontic origin. History-taking and clinical examination provide clues to determine the possibility of a non-endodontic lesion, although the definitive diagnosis can only be rendered based on histologic examination. In our case series, we present four cases of hematolymphoid neoplasms that radiographically mimicked endodontic lesions. All the cases initially underwent endodontic treatment, but the lesions failed to resolve. In one case, the clinician suspected a diagnosis of lymphoma based on the patient's history. In the other cases, the clinicians' impression was that the lesions originated from endodontic issues. We present two cases of diffuse large B-cell lymphoma, a case of a plasma cell neoplasm, and a case of Langerhans cell histiocytosis, along with a literature review of three entities when found in the oral cavity as well as review of hematolymphoid neoplasm mimicking endodontic lesion previously reported in literature.

A Diagnostic Dilemma and Classification Conundrum: Atypical Histiocytic Neoplasm Presenting as a Calvarial Mass

Histiocytic disorders are a wide range of disorders arising from abnormal proliferation and infiltration of dendritic cells. The Histiocyte Society has arranged the disorders into five main groups: L, C, M, R, and H. We present a case in which an elderly woman presented with a solitary osseous lesion in her skull in the right anterior calvarium. Biopsy and histological studies were strongly positive for cyclin D1; positive for CD68, S100, and ZBTB46; weakly positive for OCT2; and equivocal for ALK1 and CD163. Genomic studies also identified KRAS and GPS2 mutations. KRAS-positive genomic analysis favors a diagnosis of histiocytoma, while the solitary calvarium and spontaneous resolution with remission favor a diagnosis of Langerhans cell histiocytosis (LHC). Despite the strong clinical evidence favoring LCH, our patient's clinical and histologic features did not fit any of the five histiocytic categories and were classified as an atypical histiocytic disorder.

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.

Langerhans cell histiocytosis: current advances in molecular pathogenesis

Langerhans cell histiocytosis (LCH) is a rare and clinically heterogeneous hematological disease characterized by the accumulation of mononuclear phagocytes in various tissues and organs. LCH is often characterized by activating mutations of the mitogen-activated protein kinase (MAPK) pathway with BRAFV600E being the most recurrent mutation. Although this discovery has greatly helped in understanding the disease and in developing better investigational tools, the process of malignant transformation and the cell of origin are still not fully understood. In this review, we focus on the newest updates regarding the molecular pathogenesis of LCH and novel suggested pathways with treatment potential.

Adult-onset Langerhans cell histiocytosis of bone: A case series highlighting a rare entity

Langerhans cell histiocytosis (LCH) is a neoplastic disorder derived from LCH precursor cells that can manifest as a single-system disease or a multisystem disorder. While extensively studied in children, LCH has received less attention in adult patients. We aimed to investigate the pathology and clinical course of LCH in adults presenting with a bone lesion. Cases of osseous LCH diagnosed in patients ≥18 in our center were analyzed. Histologic slides were reviewed, and clinical data were collated. Molecular analysis for BRAF mutation was performed in a subset. Twelve osseous LCH cases with classic morphology and CD1a+/S100+ immunophenotype were identified. Tumors occurred in six females and five males with a median age of 34 years (range: 18-77 years) and involved the craniofacial bones (4), pelvis (3), spine (2), appendicular skeleton (2), and rib (1). Radiographically, tumors appeared as ill-defined lytic lesions, often accompanied by cortical erosion and soft tissue extension, with pain being the most common presentation. On staging work-up with available data, two patients had multifocal bone lesions, two had multi-system disease, and four had solitary lesions. Two patients had prior or concurrent neoplasms, and 63 % of patients (5 out of 8) had a history of smoking. BRAF mutational analysis performed in six cases revealed a BRAFV600E mutation in one, negative result in one, and failed in four archived specimens. Our study highlights the importance of performing staging in patients with adult-onset LCH presenting as a bone lesion, as the clinical extent of the disease can vary widely among individuals.

A solitary osteolytic lesion with pathological fracture in the cervical spine - a case report

BACKGROUND

Langerhans cell histiocytosis (LCH) is a rare disorder. The treatment options vary depending on how many organs are involved and how extensive the disease is. In this report, a case of LCH with isolated 6th cervical vertebra (C6) collapse was presented. This case was treated with anterior corpectomy and instrumented fusion, followed by local radiotherapy (RT), with a good clinical outcome up to postoperative six months.

CASE PRESENTATION

This was a 47-year-old female patient with a complaint of neck pain and bilateral shoulder pain for two months before consultation. She was initially treated with analgesics, but the pain was persistent. Further radiological evaluations revealed an osteolytic lesion within the C6 vertebral body with a pathological fracture. Magnetic resonance imaging (MRI) with contrast of the cervical spine revealed diffused hypointense signal changes on the T1-weighted images and hyperintense signal changes on the T2-weighted images in the C6 vertebral body, with significant contrast-enhanced infiltration signals. Furthermore, in positron emission tomography-computed tomography (PET-CT), focal hypermetabolism and abnormal uptake signals were seen only in the C6 vertebral body. The patient underwent an anterior cervical corpectomy with instrumented fusion. The histopathological results confirmed the diagnosis of LCH. The patient reported significant pain relief on postoperative day one. Moreover, she was treated by local RT at postoperative one month. Good clinical outcomes were achieved in the form of no pain and recovery in neck mobility up to postoperative six months. No evidence of recurrence was observed at the final follow-up.

CONCLUSIONS

This case report describes a treatment option for a solitary C6 collapse with LCH managed by anterior corpectomy and instrumented fusion, followed by local RT, with a good clinical outcome at postoperative six months. More studies are needed to elucidate whether such a treatment strategy is superior to surgery or RT alone.

Treatment of Langerhans Cell Histiocytosis and Histiocytic Disorders: A Focus on MAPK Pathway Inhibitors

Histiocytic disorders are rare diseases defined by the clonal accumulation of a macrophage or dendritic cell origin. These disorders include Langerhans cell histiocytosis, Erdheim-Chester disease, juvenile xanthogranuloma, malignant histiocytoses, and Rosai-Dorfman-Destombes disease. These histiocytic disorders are a diverse group of disorders with different presentations, management, and prognosis. This review focuses on these histiocytic disorders and the role of pathological ERK signaling due to somatic mutations in the mitogen--activated protein kinase (MAPK) pathway. Over the last decade, there has been growing awareness of the MAPK pathway being a key driver in many histiocytic disorders, which has led to successful treatment with targeted therapies, in particular, BRAF inhibitors and MEK inhibitors.

Comparison of whole-body DW-MRI with 2-[18F]FDG PET for staging and treatment monitoring of children with Langerhans cell histiocytosis

PURPOSE

To assess and compare the diagnostic accuracy of whole-body (WB) DW-MRI with 2-[18F]FDG PET for staging and treatment monitoring of children with Langerhans cell histiocytosis (LCH).

METHODS

Twenty-three children with LCH underwent 2-[18F]FDG PET and WB DW-MRI at baseline. Two nuclear medicine physicians and two radiologists independently assessed presence/absence of tumors in 8 anatomical areas. Sixteen children also performed 2-[18F]FDG PET and WB DW-MRI at follow-up. One radiologist and one nuclear medicine physician revised follow-up scans and collected changes in tumor apparent diffusion (ADC) and standardized uptake values (SUV) before and after therapy in all detectable lesions. 2-[18F]FDG PET results were considered the standard of reference for tumor detection and evaluation of treatment response according to Lugano criteria. Sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy of WB DW-MRI at baseline were calculated, and the 95% confidence intervals were estimated by using the Clopper-Pearson (exact) method; changes in tumor SUVs and ADC were compared using a Mann-Whitney U test. Agreement between reviewers was assessed with a Cohen's weighted kappa coefficient. Analyses were conducted using SAS software version 9.4.

RESULTS

Agreement between reviewers was perfect (kappa coefficient = 1) for all analyzed regions but spine and neck (kappa coefficient = 0.89 and 0.83, respectively) for 2-[18F]FDG PET images, and abdomen and pelvis (kappa coefficient = 0.65 and 0.88, respectively) for WB DW-MRI. Sensitivity and specificity were 95.5% and 100% for WB DW-MRI compared to 2-[18F]FDG PET. Pre to post-treatment changes in SUVratio and ADCmean were inversely correlated for all lesions (r: -0.27, p = 0·06) and significantly different between responders and non-responders to chemotherapy (p = 0.0006 and p = 0·003 for SUVratio and ADCmean, respectively).

CONCLUSION

Our study showed that WB DW-MRI has similar accuracy to 2-[18F]FDG PET for staging and treatment monitoring of LCH in children. While 2-[18F]FDG PET remains an approved radiological examination for assessing metabolically active disease, WB DW-MRI could be considered as an alternative approach without radiation exposure. The combination of both modalities might have advantages over either approach alone.

Langerhans Cell Histiocytosis of the Head and Neck: Experience at a Rural Tertiary Referral Center

OBJECTIVES

Retrospectively analyze head and neck Langerhans Cell Histiocytosis at a rural tertiary referral center and compare results with previously published data.

METHODS

Electronic health record review was performed from 2003 to 2019. Patients with biopsy proven LCH with primary head and neck involvement were included. Demographics, presentation, imaging characteristics, treatment modality, delay in diagnosis (DD, ≥60 days), and outcomes were analyzed and reported.

RESULTS

Twenty-four patients were included. The most common presenting symptoms were otorrhea (n = 6) and scalp pain or swelling (n = 6). All patients had bony involvement. The most common site was facial or skull lesions (n = 20). Most skull lesions (75%) demonstrated CNS risk. Six patients were treated with primary surgery, 15 with primary chemotherapy, and 3 with surgery plus adjuvant chemotherapy. Nine patients experienced relapse of disease with median time to documented relapse of 11.4 months; all were treated with salvage chemotherapy to achieve complete remission (median follow-up: 72 months). Patients most likely to relapse were those with multisystem disease (5/7, 71.4%), temporal bone lesions (4/7, 57.1%), and DD (7/12, 58.3%). Of the 9 total patients who experienced relapse, 78% had a delay in diagnosis.

CONCLUSIONS

LCH is a complex disease process in which diagnosis can be delayed if not considered in the differential. Within the head and neck, the skull, including isolated temporal bone involvement, is the most common site of involvement. Treatment modality does not appear to have an influence on relapse rates. Relapse was more likely to occur in the first year after treatment and close monitoring is required.

Adult Onset Langerhans Cell Histiocytosis: Clinical Characteristics and Treatment Outcomes

PURPOSE

Langerhans cell histiocytosis (LCH) is a rare disease that can affect all tissues and organs. Our study evaluated the clinical characteristics and treatment outcomes of adult-onset LCH patients in a tertiary center.

MATERIALS AND METHODS

Adult patients diagnosed with LCH were retrospectively evaluated. Their initial symptoms, stratification according to disease involvement, treatment details, treatment responses, and overall and progression-free survival (PFS) were analyzed.

RESULTS

Thirty-three patients were included. There were 21 single system LCH, 10 multisystem LCH, and 2 pulmonary LCH patients. Patients with single system unifocal involvement were successfully treated with local therapies such as surgery and radiotherapy. Most of the multisystem LCH patients and patients with single system multifocal involvement were treated with systemic chemotherapy. Cladribine was the first choice in 10 out of 11 patients who received chemotherapy. Among all patients, the overall response rate (ORR) was 97%. Among those who had cladribine in the first-line the ORR was 81%. All these patients achieved a complete remission and were alive at the last visit. The median follow-up was 38 (range, 2-183) months. The median PFS has not yet been reached. Ten-year PFS was 90.9%.

CONCLUSION

Besides successful local treatments with surgery and radiotherapy, our study provides information for front-line cladribine treatment.

Ophthalmic histiocytic lesions (diseases of the L group): A multicenter clinicopathological study of 18 cases and review of literature

INTRODUCTION

Langerhans cell histiocytosis (LCH) and Erdheim-Chester disease (ECD) are rare histiocytic disorders in the L (Langerhans) group diseases. They range from self-limited benign diseases to lethal disseminated forms.

METHODS

This retrospective study was conducted in 3 tertiary hospitals in Saudi Arabia and Brazil. Histopathological records were searched for all patients diagnosed with ocular and periocular histiocytic disorders from January 1993 to December 2018. Histopathological slides and medical files were reviewed for data collection and simple analysis of demographics, clinical manifestations, and management. The relevant literature is reviewed.

RESULTS

Twenty-two eyes of 18 patients with biopsy-proven histiocytic disorders in the L group were included. Female-to-male ratio was 1.25:1. Average age at presentation was 14 years (range, 1-54). LCH was diagnosed in 14 eyes, while eight eyes had ECD. All LCH cases were unilateral and confined to the bone as cases of eosinophilic granuloma (EG), while patients with ECD were bilateral. Commonest presentations in EG and ECD were eyelid swelling (85.7%) and periocular xanthomas (75%), respectively. Orbit was involved in 100% of EG cases, with bony erosion in 54.5%. Relevant systemic involvement was found in 100% of ECD and 21% of EG cases. Surgical intervention was needed in 16 of the 22 eyes (72.7%). All EG and 25% of patients with ECD required surgical excision.

CONCLUSIONS

Histiocytic disorders are a rare group of diseases, including the L group. Relevant systemic associations require specific and selective therapy. A high clinical index and multidisciplinary collaboration are essential for the proper evaluation and management of these patients.

The added value of skeletal surveys in the initial evaluation of children diagnosed with Langerhans cell histiocytosis in the era of staging 18 F-FDG PET/CT: A retrospective study

OBJECTIVE

Currently, there is no consensus protocol on the initial staging evaluation for Langerhans cell histiocytosis (LCH). Our institutional protocol consists of a skeletal survey and a whole-body positron emission tomography with 2-deoxy-2-[fluorine-18] fluoro-D-glucose integrated with computed tomography (FDG PET/CT) study. The utility of the PET/CT lies in its sensitivity in detecting osseous and extra-osseous lesions, and in determining the baseline metabolic activity of LCH lesions to assess treatment response. However, the added utility of the skeletal survey in staging LCH is unclear. Therefore, this study retrospectively assessed the added diagnostic value of skeletal surveys in patients with baseline PET/CTs for initial staging of LCH.

METHODS

We retrospectively searched the medical records of all patients less than or equal to 18 years old at a large children's hospital (May 2013 to September 2021). The inclusion criteria were (a) biopsy-proven diagnosis of LCH and (b) initial staging PET/CT and skeletal survey performed less than or equal to 1 month apart. A blinded pediatric radiologist reviewed the skeletal surveys and another reviewed the PET/CTs in identifying LCH osseous lesions.

RESULTS

Our study cohort consisted of 49 children with 86 LCH osseous lesions. In non-extremity locations, PET/CT identified 70/70 (100%) osseous lesions, while skeletal surveys detected 43/70 (61.4%) osseous lesions. In the extremities, PET/CT identified 13/16 (81.3%) osseous lesions, while skeletal surveys detected 15/16 (93.8%) osseous lesions.

CONCLUSION

Skeletal surveys increased the detection rate of osseous lesions in the extremities, but added no diagnostic value to the detection of osseous lesions in non-extremity locations. Therefore, we propose to abbreviate the skeletal survey to include only extremity radiographs.

Notch-dependent cooperativity between myeloid lineages promotes Langerhans cell histiocytosis pathology

Langerhans cell histiocytosis (LCH) is a potentially fatal neoplasm characterized by the aberrant differentiation of mononuclear phagocytes, driven by mitogen-activated protein kinase (MAPK) pathway activation. LCH cells may trigger destructive pathology yet remain in a precarious state finely balanced between apoptosis and survival, supported by a unique inflammatory milieu. The interactions that maintain this state are not well known and may offer targets for intervention. Here, we used single-cell RNA-seq and protein analysis to dissect LCH lesions, assessing LCH cell heterogeneity and comparing LCH cells with normal mononuclear phagocytes within lesions. We found LCH discriminatory signatures pointing to senescence and escape from tumor immune surveillance. We also uncovered two major lineages of LCH with DC2- and DC3/monocyte-like phenotypes and validated them in multiple pathological tissue sites by high-content imaging. Receptor-ligand analyses and lineage tracing in vitro revealed Notch-dependent cooperativity between DC2 and DC3/monocyte lineages during expression of the pathognomonic LCH program. Our results present a convergent dual origin model of LCH with MAPK pathway activation occurring before fate commitment to DC2 and DC3/monocyte lineages and Notch-dependent cooperativity between lineages driving the development of LCH cells.

Adult onset xanthogranuloma of the eyelid

Purpose

To report a rare case of an eyelid lesion in an adult, with histological features of juvenile xanthogranuloma (JXG).

Observations

Juvenile xanthogranuloma primarily affects the skin of infants and young children. It infrequently can involve the structures of the eye and orbit and rarely occurs in individuals beyond the second decade of life. We present a case of adult onset xanthogranuloma (AXG) involving the eyelid of a 29-year-old female. This lesion required management with multiple treatment modalities.

Conclusions

This is a rare example of an eyelid xanthogranuloma in an adult. As such, JXG-like lesions should be included as a differential diagnosis for lesions of the eye and orbit in adults. Surgical management may be required if there is no response to intralesional steroids.

Incidence, prevalence and survival in patients with Langerhans cell histiocytosis: A national registry study from England, 2013-2019

This analysis is the largest population-based study to date to provide contemporary and comprehensive epidemiological estimates of all third edition of the International Classification of Diseases for Oncology (ICD-O-3) coded Langerhans cell histiocytosis (LCH) from England. People of all ages were identified from the National Cancer Registration Dataset using ICD-O-3 morphologies 9751-9754 for neoplasms diagnosed in 2013-2019. A total of 658 patients were identified, of whom 324 (49%) were children aged <15 years. The age-standardised incidence rate was 4.46 (95% confidence interval [CI] 3.99-4.98) per million children and 1.06 (95% CI 0.94-1.18) per million adults aged ≥15 years. Prevalence of LCH was 9.95 (95% CI 9.14-10.81) per million persons at the end of 2019. The 1-year overall survival (OS) was 99% (95% CI 97%-100%) for children and 90% (95% CI 87%-93%) for adults. Those aged ≥60 years had poorer OS than those aged <15 years (hazard ratio [HR] 22.12, 95% CI 7.10-68.94; p < 0.001). People in deprived areas had lower OS than those in the least deprived areas (HR 5.36, 95% CI 1.16-24.87; p = 0.03). There will inevitably be other environmental factors and associations yet to be identified, and the continued standardised data collection will allow further evaluation of data over time. This will be increasingly important with developments in LCH management following the large collaborative international trials such as LCH IV.

Histiocytic Disorders of Childhood

Histiocytic disorders of childhood represent a wide spectrum of conditions that share the common histologic feature of activated or transformed "histiocytes." Langerhans cell histiocytosis (LCH) is the most common, with an incidence of approximately 5 per million children. LCH may be difficult to distinguish from more ubiquitous causes of skin rashes, bone pain, or fever. Current chemotherapy fails to cure more than 50% of children with multifocal disease, and treatment failure is associated with increased risks of long-term sequelae. Somatic activating mitogen-activated protein kinase (MAPK) pathway-activating mutations (most often BRAFV600E) have been identified in hematopoietic precursors in patients with LCH. Opportunities to improve outcomes with targeted therapies are under investigation. Juvenile xanthogranuloma (JXG) and Rosai-Dorfman disease (RDD) are less common than LCH and are distinguished by specific histologic and clinical features. Recurrent MAPK pathway gene mutations are also identified in JXG and RDD. In many cases, these conditions spontaneously resolve, but disseminated disease can be fatal. Although there has been historic debate regarding the nature of these conditions as inflammatory versus neoplastic, LCH, JXG, and RDD are now considered myeloid neoplastic disorders. In contrast, hemophagocytic lymphohistiocytosis (HLH) is clearly a disorder of immune dysregulation. HLH is characterized by extreme immune activation driven by hyperactivated T cells. HLH arises in approximately 1 child per million and is nearly universally fatal without prompt recognition and immune suppression. Outcomes of treated children are poor, with approximately 60% survival. Emapalumab, which targets interferon-γ signaling, was recently approved for patients with recurrent or refractory HLH, and additional cytokine-directed therapies are under investigation.

Ultrasonographic analysis of Langerhans cell histiocytosis in children: a report of 55 cases

OBJECTIVE

To explore the value of ultrasonography in the diagnosis and treatment of Langerhans cell histiocytosis (LCH) in children.

METHOD

The clinical and imaging features of 55 children with pathologically confirmed LCH were retrospectively analyzed.

RESULTS

Thirteen patients had bone LCH and 42 had multisystem LCH. Among the 13 cases of bone LCH, 8 cases involving the skull and 2 involving the scapula were characterized by osteolytic bone destruction, 1 case involving the clavicle and 1 involving the iliac bone showed multiple irregular bone destruction, and 1 case involving the tibia showed local hypoechoic cortical bone. Soft tissue echo filling was present in the local areas of bone destruction. Among the 42 cases of multisystem LCH, 33 involved the bone, 35 showed an enlarged liver, 15 involved the spleen, 2 involved the pancreas, 3 involved the lung, 3 involved the thymus, and 21 affected the lymph nodes in different regions.

CONCLUSIONS

Ultrasonography of the flat bones in children with LCH mainly showed punched-out osteolytic bone destruction. Long bone lesions were characterized by fan shell changes in the endosteum of long bones, and some also showed bone destruction. Multisystem LCH can affect almost any organ. Ultrasonography is important for early diagnosis.

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.

Langerhans cell histiocytosis of the rib in an adult: A case report and review of the literature

INTRODUCTION AND IMPORTANCE

Langerhans cell histiocytosis (LCH) is a rare neoplastic hyperplasia with an unknown etiology. It is clinically rare for patients with solitary rib lesion and pathological fracture. In this article, we report a case of LCH in solitary involvement of rib and provide a review of the available literature.

CASE PRESENTATION

A 24-year-old female patient complained of right chest and back pain for 10 days. CT showed a fracture in the right 6th rib. Findings on X-ray, and CT were suggestive of homogeneous osteolytic lesion of the right 6th rib. The rib tumor was then resected and the surrounding muscles and soft tissues were accordingly resected.

CLINICAL DISCUSSION

The patient was diagnosed with pathological rib fracture, and the patient was pathologically diagnosed with LCH. After surgery, no local recurrence or distant metastasis was reported during the one-year follow-up.

CONCLUSIONS

Most of the solitary tumorous lesions in rib in adults call for various differential diagnoses. Although single-site, single-system LCH of the rib is one of the rarest causes of bone tumor in adults, it can be treated successfully with surgical intervention. LCH should be considered in the diagnosis of an adult patient with a rib mass.

Hypothalamic syndrome

Hypothalamic syndrome (HS) is a rare disorder caused by disease-related and/or treatment-related injury to the hypothalamus, most commonly associated with rare, non-cancerous parasellar masses, such as craniopharyngiomas, germ cell tumours, gliomas, cysts of Rathke's pouch and Langerhans cell histiocytosis, as well as with genetic neurodevelopmental syndromes, such as Prader-Willi syndrome and septo-optic dysplasia. HS is characterized by intractable weight gain associated with severe morbid obesity, multiple endocrine abnormalities and memory impairment, attention deficit and reduced impulse control as well as increased risk of cardiovascular and metabolic disorders. Currently, there is no cure for this condition but treatments for general obesity are often used in patients with HS, including surgery, medication and counselling. However, these are mostly ineffective and no medications that are specifically approved for the treatment of HS are available. Specific challenges in HS are because the syndrome represents an adverse effect of different diseases, and that diagnostic criteria, aetiology, pathogenesis and management of HS are not completely defined.

Human dendritic cells in cancer

Dendritic cells (DCs) are professional antigen-presenting cells, orchestrating innate and adaptive immunity during infections, autoimmune diseases, and malignancies. Since the discovery of DCs almost 50 years ago, our understanding of their biology in humans has increased substantially. Here, we review both antitumor and tolerogenic DC responses in cancer and discuss lineage-specific contributions by their functionally specialized subsets, including the conventional DC (cDC) subsets cDC1 and cDC2, the newly described DC3, and the plasmacytoid DCs (pDCs), focusing on the human setting. In addition, we review the lineage-unrestricted "mature DCs enriched in immunoregulatory molecules" (mregDC) state recently described across different human tumors.

Analysis of thyroid involvement in children and adult Langerhans cell histiocytosis: An underestimated endocrine manifestation

BACKGROUND

Langerhans cell histiocytosis (LCH) is a rare disease caused by the clonal expansion of CD1a+/CD207+ LCH cells. The thyroid involvement in LCH has mostly been described in case reports.

METHODS

We retrospectively evaluated the clinical characteristics, diagnosis, and treatment of 27 children and adult patients with thyroid LCH in our center between 2010 and 2021.

RESULTS

The incidence of thyroid LCH was 14.00% (7/50) in children and 10.10% (20/198) in adults, respectively. Among patients with thyroid involvement, 81.5% presented with diabetes insipidus (DI) as the first symptom, and 51.9% complained of neck swelling or mass. Children and adults with thyroid LCH had higher frequencies of the hypothalamic-pituitary axis (HPA) (children: 100% vs. 62.8%, P=0.05; adult: 95% vs. 42.1%, P<0.001), the lung (children: 85.7% vs. 25.6%, P=0.004; adult: 70% vs. 50.6%, P=0.099), and a lower frequency of bone (children: 14.3% vs. 55.8%, P=0.049; adult: 45% vs. 73.6%, P=0.008) involvement than patients without thyroid involvement. Patients with thyroid LCH had a higher frequency of primary hypothyroidism and a lower frequency of euthyroidism than patients without it. The two major types of ultrasound imaging were diffuse (55%) and nodular type (45%). The standardized uptake value of thyroid on 18-F-fluorodeoxyglucose positron emission tomography/computed tomography was 5.3-12.8. The diagnoses were confirmed using thyroid aspiration (54.5%) or surgery (45.5%). In addition, thyroid LCH combined with papillary thyroid carcinoma was not rare (2/27).

CONCLUSION

Thyroid involvement in LCH is not rare. Furthermore, identifying thyroid involvement can facilitate the pathological diagnosis of LCH. Therefore, the possibility of thyroid LCH should be fully investigated in patients with DI, primary hypothyroidism, abnormal thyroid ultrasound results, and multi-system disease. In addition, thyroid aspiration can confirm suspected thyroid LCH. Finally, special attention should be paid to evaluating HPA and pulmonary involvement in thyroid LCH.

Hemophagocytic Lymphohistiocytosis in Langerhans Cell Histiocytosis: A Case Series and Literature Review

Langerhans cell histiocytosis (LCH) is characterized pathologically by langerin-positive (CD207+) dendritic cell proliferation and is considered by some as a myeloid neoplastic disorder. Hemophagocytic lymphohistiocytosis (HLH) is associated with immune dysregulation characterized by the accumulation of activated macrophages and hypercytokinemia. However, these 2 histiocytosis rarely coexist. Currently, the etiology, risk factors, optimal therapy, and outcomes of LCH-HLH remain unclear. We reviewed the medical records of 7 LCH-HLH patients from our hospital and analyzed 50 LCH-HLH patients reported in scientific literature. The median age of LCH onset of these 57 LCH-HLH patients was 1 year, and 91% (52/57) of patients diagnosed as LCH were less than 2 years old. Fifty-six LCH-HLH patients belonged to the multisystem LCH category and 84% (47/56) patients had risk-organ involvement. Twenty-three LCH-HLH patients were complicated with infection and 3 patients had a primary pathogenic mutation of HLH. Overall, 90% of LCH patients developed HLH at the diagnosis or during chemotherapy. Of the 57 LCH-HLH patients, 15 died. Multisystem LCH patients with risk-organ involvement under 2 years old were most likely to develop HLH when complicated with infection at diagnosis or during chemotherapy. Identifying LCH-HLH patients during early stages and treating them with prompt chemotherapy, hematopoietic stem cell transplantation, or supportive therapies are important for better survival.

Case Report: Early Association of Vemurafenib to Standard Chemotherapy in Multisystem Langerhans Cell Histiocytosis in a Newborn: Taking a Chance for a Better Outcome?

Langerhans cell histiocytosis (LCH) is due to aberrant monoclonal proliferation and accumulation of dendritic cells, ranging from a self-limiting local condition to a rapidly progressive multisystem disease with poor prognosis. Pathogenic cells originate from a myeloid-derived precursor characterized by an activation of the MAPK/ERK signaling pathway in about 70% of cases. In particular, BRAF V600E mutation is usually associated with a more severe clinical course and poor response to chemotherapy. We report on a newborn with multisystem LCH in life-threatening medical conditions. At diagnosis, the patient was successfully treated with the early association of BRAF inhibitor Vemurafenib to standard chemotherapy representing a new approach in first-line treatment. A rapid clinical improvement with a prompt fever regression from day 2 and complete resolution of skin lesions by week 2 were observed; laboratory data normalized as well. Vemurafenib was discontinued after 12 months of treatment. No signs of relapse occurred after 12 months of discontinuation. This case indicates that early combination of target therapy with standard treatment may induce rapid response and prolonged disease remission without significant toxicities in infants. This approach represents a valid and safe option as first-line treatment in multisystem disease, especially in high-risk patients.

Clinical and prognostic characteristics of 95 cases of Langerhans cell histiocytosis in children: a single-institute experience from 2013 to 2020

BACKGROUND

This study aimed to understand the clinical characteristics and outcomes of children with Langerhans cell histiocytosis (LCH) in China.

METHODS

We conducted a retrospective study of 95 paediatric patients with LCH in West China Second University Hospital of Sichuan University between July 2013 and August 2020.

RESULTS

The onset age of multisystem LCH (MS-LCH) patients with risk organ (RO) involvement was younger than that of MS-LCH without RO involvement (p = .002) and single system LCH (p < .001) patients; bone was the most frequently involved organ, followed by the skin. Of all, the BRAF-V600E mutation was detected in 48 out of 84 patients who underwent gene analysis. Additionally, in our study, BRAF p.N486_T491 > K, BRAF p.L485_P490delinsF, BRAF p.R506_K507insLLR, ARAF p.Q349_F351delinsL and MAP2K1 p.Q58_E62del were known mutations in the mitogen-activated protein kinase (MAPK) pathway. The BRAF-V600E genotype in the tissue and plasma prior to therapy were detected in 16 patients, and the concordance was only 37.5% (6/16). According to the modified LCH-III-based-protocol, JLSG-02 protocol chemotherapy, and vemurafenib, the estimated five-year overall survival, event-free survival (EFS) and cumulative reactivation rates of 95 patients were 98.8%, 74.6% and 24.5%, respectively. The EFS rate in good responders was better than that in poor responders at 12-week (HR = 0.022, 95%CI 0.002-0.231, p = .002), and EFS was not affected by age, RO involvement or BRAF-V600E mutation. Regarding sequelae, nine patients had central diabetes insipidus and two had growth retardation.

CONCLUSIONS

In this study, LCH was a highly heterogeneous disease characterized molecularly by MAPK-pathway activating mutations. Vincristine, prednisone and cytarabine-based chemotherapy combined with vemurafenib improved the prognosis of childhood LCH. In future, prospective clinical trials and novel therapeutic strategies should be developed to improve outcomes in paediatric patients with LCH.KEY MESSAGEChildren with Langerhans cell histiocytosis in China present highly heterogeneous clinical characteristics, with up to 60% of cases harbouring mutations in MAPK pathway.Treatment response at 12-week is associated with EFS in our study.Vincristine, prednisone and cytarabine-based chemotherapy combined with vemurafenib improved the prognosis of Chinese childhood LCH, but the reactivation rate is still high.

Histiocytic Neoplasms, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

Histiocytic neoplasms are rare hematologic disorders accounting for less than 1% of cancers of the soft tissue and lymph nodes. Clinical presentation and prognosis of these disorders can be highly variable, leading to challenges for diagnosis and optimal management of these patients. Treatment often consists of systemic therapy, and recent studies support use of targeted therapies for patients with these disorders. Observation ("watch and wait") may be sufficient for select patients with mild disease. These NCCN Guidelines for Histiocytic Neoplasms include recommendations for diagnosis and treatment of adults with the most common histiocytic disorders: Langerhans cell histiocytosis, Erdheim-Chester disease, and Rosai-Dorfman disease.

Ophthalmic histiocytic lesions: a baseline demographic and clinicopathological study of 28 cases from two eye centers

PURPOSE

Ophthalmic histiocytic lesions comprise a heterogeneous rare group of disorders that are characterized by an abnormal proliferation of histiocytes and may affect all age groups of both sexes. The aim of this study was to highlight the basic demographic, clinical, and histopathological characteristics of this rare group of diseases in ophthalmic practice, which has not been previously studied in this area. Only individual cases have been previously reported.

METHODS

This was a retrospective study of all biopsied ocular and periocular histiocytic lesions from two centers, King Khaled Eye Specialist Hospital (KKESH) and King Abdulaziz University Hospital (KAUH) in Riyadh, Saudi Arabia, from January 1993 to December 2018. The histopathological diagnosis was confirmed, and the cases were re-classified by reviewing all histopathological slides. The corresponding demographic and clinical data were analyzed. A relevant literature review was also carried out for comparison of our collected analyzed data to published data and to draw our own conclusions.

RESULTS

A total of 34 ocular/periocular histiocytic lesions in 28 patients who were mostly Saudis (92.9%) were included. The male-to-female ratio was 4:3. The median age at presentation was 6.4 years (range: 2.8-35 years). Twenty-two patients had unilateral involvement, and six patients had bilateral lesions. In patients with Langerhans cell histiocytosis (LCH; L group), the most common presenting findings were eyelid swelling (75%), periocular tenderness (37.5%), proptosis/globe displacement (37.5%) eyelid erythema (25%), and orbital pain (12.5%). In patients with Rosai Dorfman disease (RDD; R group), proptosis/globe displacement occurred in all patients and 80% had decreased vision. Patients in the C group (Cutaneous non-LCH histiocytoses) had variable clinical features because of the different locations of the histiocytic lesions, with the majority involving the eyelids (66.7%). Diagnosis was accurately reached clinically in 38.8%, 33.7%, and 46.7% of patients in the L, C, and R groups, respectively. Overall, the clinical diagnosis was in concordance with the histopathologic diagnosis in 14 out of 34 lesions (41.2%).

CONCLUSIONS

Histiocytic disease is more likely to be overlooked clinically owing to its rarity. In the C group, juvenile xanthogranuloma (JXG) was the most commonly encountered histiocytic lesion and had a tendency to present at a later age with extremely rare intraocular involvement in contrast to previously published reports. The median age at presentation was higher in group R. All patients in group L had strictly unilateral disease, while RDD (group R) was most commonly bilateral. Future research on genetic aspects, management, and prognosis is necessary.

Recommendations for Managing Adults With Histiocytic Neoplasms: New NCCN Guidelines

The histiocytoses, a group of clonal and reactive conditions, arise from monocytic macrophage or dendritic cell lineages. The current NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Histiocytic Neoplasms reflect the most up-to-date, evidence-based data relating to the evaluation and management of this disease. Specifically, the guidelines focus on adult Langerhans cell histiocytosis, Erdheim-Chester disease, and Rosai-Dorfman disease. Because these disorders are rare, challenges have arisen regarding clinical suspicion, histologic diagnosis, treatment, and molecular subtyping. Future versions of the NCCN Guidelines will address the diagnosis and management of pediatric patients, as well as malignant histiocytosis.

Langerhans cell histiocytosis in adults: a retrospective, single-center case series

Langerhans cell histiocytosis is rare in adults, and most of what we know about its diagnosis and treatment comes from pediatric studies. We report clinical findings and results of treatment in a retrospective series of 63 consecutive adult patients (18-76 years old), treated at our pediatric unit from 1990 to 2020 using the same approach as for children. Patients were classified as having single-system disease (SS-LCH) in 41 cases, which was unifocal in 34 of them and multifocal in 7, or multisystem disease (MS-LCH) in 17 and primary pulmonary (pLCH) in 5. Twenty patients also had diabetes insipidus. A "wait and see" strategy was recommended after biopsy/surgery for patients with unifocal SS-LCH. Systemic treatment was proposed for cases of SS-LCH involving "special sites" or with multifocal disease, and in cases of MS-LCH. EFS and OS for the cohort as a whole were 62.2% and 100%, respectively, at 5 years and 52.5% and 97.6% at 10 years. Three patients died due to the damage caused by the multiple therapies administered. The rate of disease reactivation was high (affecting 40% of cases), with several reactivations over the years despite multiple lines of treatment. Though clinical history of LCH may differ between adults and children, in the absence of specific, tailored protocols, clinical approach to adult cases may draw on pediatric experience. Patients with limited disease have a good prognosis without any need for systemic therapy. Potentially greater toxicity in adults of systemic treatments generally used in pediatric setting should be borne in mind.

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.

Additive Prognostic Impact of Gastrointestinal Involvement in Severe Multisystem Langerhans Cell Histiocytosis

OBJECTIVE

To evaluate the prognostic impact of gastrointestinal involvement on the survival of children with Langerhans cell histiocytosis (GI-LCH) registered with the international clinical trials of the Histiocyte Society.

STUDY DESIGN

This was a retrospective analysis of 2414 pediatric patients registered onto the consecutive trials DAL-HX 83, DAL-HX 90, LCH-I, LCH-II, and LCH-III.

RESULTS

Among the 1289 patients with single-system LCH, there was no single case confined to the GI tract; 114 of 1125 (10%) patients with multisystem LCH (MS-LCH) had GI-LCH at initial presentation. GI-LCH was significantly more common in children aged <2 years at diagnosis (13% vs 6% in those aged >2 years; P < .001) and in those with risk organ involvement (15% vs 6% in those without risk organ involvement; P < .001). The 5-year overall survival (OS) in patients without risk organ involvement was excellent irrespective of GI disease (98% vs 97% in patients with GI-LCH; P = .789). In patients with risk organ involvement, the 5-year OS was 51% in 70 patients with GI-LCH vs 72% in 394 patients without GI-LCH (P < .001).

CONCLUSIONS

GI-LCH has an additive unfavorable prognostic impact in children with MS-LCH and risk organ involvement. The emerding need for more intensive or alternative treatments mandates prospective evaluation.

Langerhans cell histiocytosis: Case report and literature review

La histiocitosis de células de Langerhans comprende un grupo heterogéneo de enfermedades inflamatorias cuyos principales componentes celulares son las células dendríticas y los macrófagos. El infiltrado inflamatorio puede afectar la piel y otros órganos, y el resultado clínico varía de leve a letal, dependiendo del subconjunto de células involucradas y el compromiso multisistémico. La demora en el diagnóstico puede ocurrir debido a su presentación inespecífica y a que los médicos tratantes no suelen sospecharla. Se reporta el caso de una lactante mayor a la cual, a pesar de múltiples consultas con síntomas inespecíficos pero característicos de la enfermedad, solamente se le pudo hacer el diagnóstico gracias a los hallazgos histopatológicos.

Clinical characteristics and outcomes of Langerhans cell histiocytosis at a single institution in Thailand: a 20-year retrospective study

Background

Langerhans cell histiocytosis (LCH) is a rare disease characterized by the various systems involved and clinical manifestations with a wide range of symptoms.

Objectives

To describe clinical characteristics, imaging, treatment, and outcomes of pediatric LCH at Phramongkutklao Hospital, Bangkok, Thailand.

Methods

We conducted a 20-year retrospective review of the medical records of patients diagnosed with LCH from birth to 21 years old from January 1, 1997, to December 31, 2016.

Results

In all, 14 patients with median age of 2.5 years were studied. Six (43%) patients had single-system (SS) LCH. Five patients (63%) with multisystem (MS) LCH (n = 8. 57%) had risk-organ involvement (RO+). All patients had plain X-ray imaging of their skull with 11 (79%) showing abnormal findings. Tc-99m bone imaging and fluorodeoxyglucose F18 (FDG) positron emission tomography (PET)-computed tomography (CT) demonstrated abnormal findings in 8 (89%) and 4 (29%) patients, respectively. The 5-year event-free survival (EFS) for patients with RO+ MS-LCH was less than that for those without risk-organ involvement (RO-) MS-LCH and SS-LCH (20% vs. 100%, P = 0.005). Hematological dysfunction, hypoalbuminemia, and conjugated hyperbilirubinemia may be worse prognostic factors for RO+ MS-LCH.

Conclusion

FDG-PET-CT might have a greater accuracy to detect LCH disease than conventional plain X-ray and Tc-99m bone imaging. RO+ MS-LCH has been encountered with relapse and poor outcomes. Hematopoietic involvement, hypoalbuminemia, and conjugated hyperbilirubinemia may be worse prognostic factors for RO+ MS-LCH.

A clinical approach to parasellar lesions in the transition age

Many reviews have summarised the pathology and management of the parasellar region in adult patients, although an analysis of these aspects in the transition years, from puberty onset to the age of peak bone mass, has been lacking. A comprehensive search of English-language original articles, published from 2000 to 2020, was conducted in the MEDLINE database (December 2019 to March 2020). We selected all studies regarding epidemiology, diagnosis and management of the following parasellar lesions: germinoma, craniopharyngioma, Langerhans cell histiocytosis, optic glioma, hypothalamic hamartoma, tuber cinereum hamartoma, cranial chordoma, Rathke cleft cyst, hypophysitis and hypothalamitis during the transition age from childhood to adulthood. In the present review, we provide an overview of the principal parasellar lesions occurring in the transition age. Symptoms are usually a result of the mass effect of the lesions on nearby structures, as well as anterior pituitary deficits. Diabetes insipidus occurs frequently in these patients. In this age group, pubertal developmental disorders may be more evident compared to other stages of life. Parasellar lesions in the transition age mostly include neoplastic lesions such as germinomas, hamartomas, optic gliomas, craniopharyngiomas Langerhans cell histiocytosis and chordomas, and rarely inflammatory lesions (hypophysitis, hypothalamitis). There are limited data on the management of parasellar lesions in the transition age. Endocrine evaluation is crucial for identifying conditions that require hormonal treatment so that they can be treated early to improve the quality of life of the individual patient in this complex age range. The clinical approach to parasellar lesions involves a multidisciplinary effort.

Long-term outcome, clinical course and treatment approaches of paediatric langerhans cell histiocytosis: A greek reference centre report

AIM

Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasia with diverse clinical behaviour. In this article, we studied the clinical course, management and long-term outcomes of a paediatric cohort treated by our reference centre.

METHODS

We retrospectively studied 66 children with LCH, consecutively diagnosed by a Greek reference centre from 1974 to 2020.

RESULTS

The patients had a median age of 3.9 (range 0.0-15.9) years, 39 and 6 patients were diagnosed with unifocal or multifocal single system disease and 14 and 7 had multisystem disease with or without risk organ involvement. No late occurrence of clinical neurodegenerative disease or diabetes insipidus were observed at a median follow-up period of 4.1 (range 0.5-27.7) years. The 10-year event-free survival and overall survival were 65.0% and 90.3% and improved significantly over a 45-year period. Survival was superior in single system than multisystem cases. BRAF V600E mutation was found in 8/14 tested patients. Reactivation occurred in 12/66 patients (18.2%); 11 achieved remission and one patient died after a second relapse.

CONCLUSION

LCH survival rates significantly increased in our cohort over time. Reactivation occurred in 18.2% patients, but no late neurodegeneration was found. The prognostic value of single system disease status vs. multisystem LCH was confirmed.

High-risk LCH in infants is serially transplantable in a xenograft model but responds durably to targeted therapy

Langerhans cell histiocytosis (LCH) is a rare hematologic neoplasm characterized by a clonal proliferation of Langerhans-like cells. Genomic profiling has identified recurrent somatic activating mutations in the mitogen-activated protein kinase pathway, which are targetable by small-molecule inhibitors. However, key questions such as the curative potential of targeted therapy and the cell of origin remain unanswered. In this study, we describe clinical outcomes of a series of pediatric patients with multisystem BRAF V600E-mutant LCH, as well as the results of accompanying murine xenograft experiments. Four infants with LCH (range, 7-11 months at diagnosis) and secondary hemophagocytic lymphohistiocytosis were referred to our institution and subsequently treated with the BRAF V600E-specific inhibitor dabrafenib. All patients achieved complete clinical responses by 8 weeks of therapy, with remissions lasting a median of 36 months (range, 27-42 months). One infant successfully discontinued therapy long-term upon achieving a molecular response by real-time quantitative polymerase chain reaction (RT-qPCR). We further characterized the disease-propagating cell population in a subset of these patients by transplanting whole bone marrow into immunodeficient mice. Xenografted animals exhibited decreased survival with hematologic abnormalities, splenomegaly, and histiocytic infiltrates in the bone marrow resembling human disease. This process could also be secondarily transplanted, resulting in a comparable disease latency with similar histologic findings. These data further support the presence of a disease-initiating cell in the bone marrow compartment. We demonstrate that despite aggressive disease behavior in a xenograft model, these patients can achieve sustained clinical remissions with targeted monotherapy, with a select subset achieving molecular responses by RT-qPCR.

MAP-Kinase-Driven Hematopoietic Neoplasms: A Decade of Progress in the Molecular Age

Mutations in members of the mitogen-activated protein kinase (MAPK) pathway are extensively studied in epithelial malignancies, with BRAF mutations being one of the most common alterations activating this pathway. However, BRAF mutations are overall quite rare in hematological malignancies. Studies over the past decade have identified high-frequency BRAF V600E, MAP2K1, and other kinase alterations in two groups of MAPK-driven hematopoietic neoplasms: hairy cell leukemia (HCL) and the systemic histiocytoses. Despite HCL and histiocytoses sharing common molecular alterations, these are phenotypically distinct malignancies that differ in respect to clinical presentation and suspected cell of origin. The purpose of this review is to highlight the molecular advancements over the last decade in the histiocytic neoplasms and HCL and discuss the impact these insights have had on our understanding of the molecular pathophysiology, cellular origins, and therapy of these enigmatic diseases as well as perspectives for future research directions.

BRAFV600E-induced senescence drives Langerhans cell histiocytosis pathophysiology

Langerhans cell histiocytosis (LCH) is a potentially fatal condition characterized by granulomatous lesions with characteristic clonal mononuclear phagocytes (MNPs) harboring activating somatic mutations in mitogen-activated protein kinase (MAPK) pathway genes, most notably BRAFV600E. We recently discovered that the BRAFV600E mutation can also affect multipotent hematopoietic progenitor cells (HPCs) in multisystem LCH disease. How the BRAFV600E mutation in HPCs leads to LCH is not known. Here we show that enforced expression of the BRAFV600E mutation in early mouse and human multipotent HPCs induced a senescence program that led to HPC growth arrest, apoptosis resistance and a senescence-associated secretory phenotype (SASP). SASP, in turn, promoted HPC skewing toward the MNP lineage, leading to the accumulation of senescent MNPs in tissue and the formation of LCH lesions. Accordingly, elimination of senescent cells using INK-ATTAC transgenic mice, as well as pharmacologic blockade of SASP, improved LCH disease in mice. These results identify senescent cells as a new target for the treatment of LCH.

Patients with both Langerhans cell histiocytosis and Crohn's disease highlight a common role of interleukin-23

Aim

To present the first case series of patients with Langerhans cell histiocytosis (LCH) also affected by Crohn's disease (CD), both of which are granulomatous diseases, and in LCH investigate the role of interleukin (IL)‐23, which is a well‐described disease mediator in CD.

Methods

A case series of three patients with LCH and CD were described; a cohort of LCH patients (n = 55) as well as controls (n = 55) were analysed for circulating IL‐23 levels; and the relation between the percentage of LCH cells in lesions and circulating IL‐23 levels was analysed in seven LCH patients.

Results

Differential diagnostic challenges for these two granulomatous diseases were highlighted in the case series, and it took up to 3 years to diagnose CD. Elevated IL‐23 levels were found in LCH patients. The amount of lesional LCH cells correlated with the levels of circulating IL‐23.

Conclusion

Both CD and LCH should be considered in patients with inflammatory gastrointestinal involvement. The IL‐23 pathway is a common immunological trait between these two granulomatous diseases.

Periodontal manifestations of Langerhans cell histiocytosis: a systematic review

Objectives

To explore the evidence of periodontal manifestations and treatment modalities in patients with Langerhans cell histiocytosis (LCH).

Material and methods

A systematic literature search was performed and the criteria for PRISMA and risk of bias assessment were applied. Human clinical studies (≥10 patients) presenting patients with LCH and periodontal findings were considered for inclusion.

Results

From 298 titles identified, six case series with a total of 1278 patients suffering from LCH were included. In these studies, oral symptoms were reported in a frequency ranging from 10 to 100%. Overall, in 216 patients (17%), oral symptoms were observed. Out of these patients, 49–100% demonstrated periodontal symptoms. The most common oral findings were pain, swelling, tooth loss/mobility, and bone lesions. Specific periodontal findings comprised varying frequencies of gingival ulcerations, increased pocket depths, and gingival bleeding. Treatment measures constituted of surgical curettage of bone lesions, soft tissue excision and/or tooth extractions, radiotherapy, systemic chemotherapy, or a combination of these approaches. Healing without recurrence of oral lesions was reported in most of the cases.

Conclusions

The available evidence on periodontal manifestations in LCH patients is heterogeneous. Several oral and periodontal findings were reported and may occur as initial symptoms and/or at later stages of the disease.

Clinical relevance

The dentist should be aware of possible oral involvement of systemic diseases such as LCH, and these manifestations may mimic periodontal disease.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00784-021-03873-0.

Langerhans Cell Histiocytosis of the Orbit: Spectrum of Clinical and Imaging Findings

OBJECTIVE

To evaluate the clinical and imaging characteristics of orbital lesions of pediatric Langerhans cell histiocytosis (LCH).

STUDY DESIGN

A retrospective analysis of clinical data and central review of magnetic resonance imaging scans in patients with LCH, enrolled into one of the consecutive international trials LCH I-III, or submitted for a second opinion between 1994 and 2015.

RESULTS

Data from 31 children (34 involved orbits) were analyzed. Orbital LCH was the only disease manifestation in 15, part of a multifocal skeletal in 5, or a multisystem LCH in 11 patients. Orbital LCH was part of the initial disease presentation in 23 or developed at relapse in 8 cases. Orbital involvement was unilateral in 28 and bilateral in 3 patients (34 affected orbits). Proptosis was present in 9 patients. Frontal and zygomatic bone were most commonly affected. All orbital lesions were extraconal. Associated extraorbital imaging findings were dural tail sign in 19, neurodegeneration in 8, and hypothalamic-pituitary mass in 3 patients. Sixteen patients (52%) had at least 1 documented disease relapse. Permanent consequences were prominent proptosis in 1, diabetes insipidus in 8, growth hormone deficiency in 2, radiologic neurodegeneration in 8, and clinical neurodegeneration in 3 patients.

CONCLUSIONS

Predominantly unilateral orbital LCH can be the only disease manifestation or part of a disseminated disease. Orbital lesions in LCH are exclusively extraconal, typically located at the roof and the lateral wall of the orbit. The optimal treatment approach of unifocal LCH of the orbit remains controversial and warrants a prospective evaluation.

Unisystem Langerhans cell histiocytosis in maxillofacial region in pediatrics: comprehensive and systematic review

BACKGROUND

The study aimed to identify, enlist, and analyze cases of unisystem LCH in the maxillofacial pediatric population to understand the clinical presentation and encourage the consideration of this rare disease in the differential diagnosis. Langerhans cell histiocytosis (LCH) is an aggressive benign condition affecting mainly the pediatric population. It can be easily masked as periodontal disease in the maxillofacial region. Early diagnosis and a systemic evaluation are of utmost importance.

METHODOLOGY

We are presenting a complete review of literature in the pediatric population according to PRISMA guidelines for clinicopathologic, histopathological, immunohistochemistry, and treatment for unisystem LCH. The risk of bias assessment across studies was done using a Case series appraisal checklist by Guo et al. 53 RESULTS: Forty-nine articles (152 cases) were selected which met our inclusion and exclusion criteria to be included in our review. Most of the patients fall in 6-12 years of age with the involvement of the mandibular body region in 40.79% cases. This disease mainly presents as erythematous gingiva, pain, swelling, and mobile teeth. Management can range from minimal intervention to chemotherapy and surgery.

CONCLUSION AND PRACTICAL IMPLICATIONS

Although this is a rare condition, it should be considered especially in the pediatric population with periodontitis type lesions and floating teeth and comprehensive management should be followed. Early diagnosis of the disease is very important.

Neuroendocrine manifestations of Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a rare inflammatory myeloid neoplasia that can affect any organ or system in the human body. It is usually diagnosed during childhood but can also affect adults. Recent studies have demonstrated involvement of the hypothalamo-pituitary axis (HPA) in a significant proportion of patients with deficiencies in both anterior and posterior pituitary function that in the majority of cases are permanent and require specific hormone replacement regimes. Central diabetes insipidus is considered the most frequent abnormality of HPA involvement in LCH and can be encountered either as isolated deficiency or along with other pituitary deficiencies. Complete hormonal evaluation of pituitary hormones and long-term follow-up of LCH patients are strongly recommended, especially when pituitary involvement is established.