Pathogenesis of Langerhans cell histiocytosis

Whole-Body Magnetic Resonance Imaging in Rheumatology

This review focuses on the most frequent whole-body MRI applications in patients with rheumatological pathologies, for which this tool can be helpful to both radiologists and clinicians. It reports technical aspects of the acquisition of both 1.5 and 3.0 T scanners. The article lists the main findings that help radiologists during the evaluation of a specific pathology, both in the diagnostic phase and during follow-up.

Langerhans cell histiocytosis mimicking acute dacryocystitis

Langerhans cell histiocytosis (LCH) is a myeloid neoplasm characterized by clonal neoplastic proliferation of Langerhans-type dendritic cells associated with an inflammatory infiltrate predominantly composed of lymphocytes and eosinophils. In this article, we present an unusual case of LCH with significant swelling in the left lacrimal sac region in a 3-year-old child, clinically mimicking acute dacryocystitis. Microscopically, it showed intense inflammatory infiltrate and histiocytes with irregular nuclei. The tumor cells were positive for S-100 protein, CD1a, and CD207 (langerin). Molecular study was positive for the V600E/E2/D mutation (EXON 15). This case emphasizes the importance of careful clinical, radiographic, and microscopic evaluation, as some neoplasms may mimic common benign lesions.

Pulmonary Langerhans Cell Histiocytosis Post-Hodgkin Lymphoma Completely Resolved With Vinblastine in a Heavy Smoker: Coincidence or Causation?

The association among Langerhans cell histiocytosis, hematolymphoid malignancies, and heavy smoking has been addressed in medical literature to identify a possible potential link. Such occurrence can pose diagnostic challenges, as well as important clinical implications for disease progression and treatment approaches. We present pulmonary Langerhans cell histiocytosis instance in a 35-year-old male patient, with a 34-pack-year smoking history and nodular sclerosing Hodgkin lymphoma stage IIB who developed multiple bilateral lung nodules. The patient completed 6 cycles of doxorubicin (Adriamycin), bleomycin, vinblastine, and dacarbazine chemotherapy and radiotherapy 2 years earlier. CT chest scans revealed numerous micronodules scattered randomly throughout the upper and lower left lung lobes. Subsequent wedge resection exhibited cellular proliferation with grooved nuclei, eosinophilic cytoplasm, and surrounding inflammatory components. Immunohistochemical staining showed positive staining for S100 and CD1a confirming a diagnosis of pulmonary Langerhans cell histiocytosis. The patient responded to a 6-week treatment with vinblastine and prednisolone. A subsequent CT scan of the lungs revealed complete resolution after 3 years. This report underscores the importance of identifying pulmonary Langerhans cell histiocytosis in heavy smokers with Hodgkin lymphoma presenting with multiple nodular pulmonary lesions. For patients with Hodgkin lymphoma and a possible genetic predisposition, smoking may contribute to the overt development of pulmonary Langerhans cell histiocytosis. Therefore, smoking cessation and careful follow-up examinations are required. Further research is recommended to elucidate the underlying mechanisms of this intriguing association.

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.

Diagnosis and treatment of isolated rib Langerhans cell histiocytosis in an adult: A case report

Langerhans cell histiocytosis (LCH) was first proposed in 1987 to define the disorder characterized by the proliferation of abnormal Langerhans cells. It is more likely to occur in children younger than 15 years of age. Single-site and single-system LCH of rib is rare in adults. We present a rare case of isolated rib LCH in a 61-year-old male patient and expound the diagnosis and treatment of the disease. A 61-year-old male patient who presented with a 15-day history of dull pain in the left chest was admitted to our hospital. PET/CT image showed obvious osteolytic bone destruction and abnormal fluorodeoxy-glucose (FDG) uptake (maximum standardized uptake value: 14.5) in the right fifth rib with local soft tissue mass formation. The patient was eventually confirmed the diagnosis of LCH by immunohistochemistry stain and treated with rib surgery. A thorough review of the literature regarding diagnosis and treatment of LCH is presented in this study.

Langerhans Cell Histiocytosis Manifests with Acute Severe Hypernatremia during Hospitalization

Central diabetes insipidus (DI) is characterized by a deficiency in arginine vasopressin (AVP), an antidiuretic hormone leading to excessive free water loss in the urine and hypernatremia. Central DI can be the first presentation of several occult diseases. However, patients with central DI who have functioning thirst mechanisms and access to water may initially exhibit normal sodium levels. We report a 57-year-old woman who was admitted to the hospital due to cholangitis. Her initial serum sodium was normal and she rapidly developed severe hypernatremia after fluid restriction. The results of the laboratory workup indicated DI, which dramatically responded to desmopressin. MRI showed an ill-defined faint hyper signal intensity in T1, T2/FLAIR lesions involving the bilateral hypothalamus. The histopathological findings confirmed the diagnosis of Langerhans cell histiocytosis (LCH) with multiorgan involvement. Serum sodium returned to normal after receiving desmopressin and water replacement therapy.

Langerin-expressing dendritic cells in pulmonary immune-related diseases

Dendritic cells (DCs) are “frontline” immune cells dedicated to antigen presentation. They serve as an important bridge connecting innate and adaptive immunity, and express various receptors for antigen capture. DCs are divided into various subclasses according to their differential expression of cell surface receptors and different subclasses of DCs exhibit specific immunological characteristics. Exploring the common features of each sub-category has became the focus of many studies. There are certain amounts of DCs expressing langerin in airways and peripheral lungs while the precise mechanism by which langerin⁺ DCs drive pulmonary disease is unclear. Langerin-expressing DCs can be further subdivided into numerous subtypes based on the co-expressed receptors, but here, we identify commonalities across these subtypes that point to the major role of langerin. Better understanding is required to clarify key disease pathways and determine potential new therapeutic approaches.

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.

[A female patient with earache, polyuria and polydipsia]

INTRODUCTION

 Langerhans cell histiocytosis is a rare inflammatory bone marrow neoplasia that frequently affects bone, lung, skin and pituitary gland. Due to its broad spectrum of clinical presentation, an appropriate diagnosis might be difficult.

HISTORY

 A 54-year-old female patient complained of pain in her right ear for 5 months. On account of similar complaints, a mastoidectomy had already been performed 3 years ago. Histology at that time revealed nonspecific inflammation. Furthermore, she reported excessive thirst.

FINDINGS AND DIAGNOSIS

 Computed tomography of the temporal bones showed osteolysis in the mastoid. Magnetic resonance imaging and bone scintigraphy assessed these changes as uncharacteristically inflammatory. Polydipsia proved to be a symptom of central diabetes insipidus in the water deprivation test. Finally, remastoidectomy provided histologic evidence of Langerhans cell histiocytosis.

THERAPY AND COURSE

 Besides systemic chemotherapy with cytarabine, the patient also received denosumab and desmopressin.

CONCLUSION

 Langerhans cell histiocytosis involving cranial bones is often associated with diabetes Insipidus. Knowledge about the distinctive constellation may lead to a more rapid diagnosis and improved prognosis.

Pulmonary Langerhans cell histiocystosis (PLCH) and lymphangioleiomyomatosis (LAM) have circulating cells with loss of heterozygosity of the TSC2 gene

BACKGROUND

Lymphangioleiomyomatosis (LAM) and pulmonary Langerhans Cell Histiocytosis (PLCH) are cystic lung diseases in which a neoplastic cell is believed to be responsible for disease pathogenesis. The neoplastic LAM cell has mutations in the Tuberous Sclerosis Complex (TSC) genes, TSC1 or TSC2, whereas the neoplastic PLCH cell may have mutations in several genes, e.g., BRAF, NRAS, MAP2K1. These mutations are not specific for PLCH and they have been described in multiple cancers. TSC1 or TSC2 mutations and loss of heterozygosity (LOH) have also been described in cancers.

RESEARCH QUESTION

Is TSC2 LOH specific to LAM or is it also found in PLCH too?

STUDY DESIGN

We recruited LAM patients (53) and Healthy Volunteers (22) and compared the presence of cells with TSC2 LOH with PLCH patients (12). Blood and urine samples were collected for analysis.

METHODS

Fluorescence-activated cell sorting (FACS) was used to identify subpopulations of cells from blood and urine samples. We isolated CD45-CD235a-, CD45-CD235a+, CD45+CD235a- cells from blood following density gradient separation. Cells were screened for TSC2 LOH at 5 microsatellites markers (i.e., kg8, D16S3395, D16S3024, D16S521, D16S291). We obtained four cell subpopulations from urine (i.e., CD44v6+CD9+; CD44v6+CD9-; CD44v6-CD9+; CD44v6-CD9).

RESULTS

Using FACS, cells were isolated from blood and urine from PLCH patients that showed TSC2 LOH. Healthy volunteers did not have cells with TSC2 LOH. As a control, cells isolated from blood and urine from LAM patients gave results similar to those reported previously. These data show that TSC2 LOH is found in patients with cystic lung diseases with potential neoplastic characteristics, as well as in patients with cancer.

INTERPRETATION

The presence of TSC2 LOH in circulating cells is not specific for LAM. The data suggest that chromosomal abnormalities affecting the TSC2 gene are found in other diseases associated with cells having cancer-like neoplastic cells.

Hypophysitis: A comprehensive overview

Hypophysitis is defined as inflammation of the pituitary gland. It is a heterogeneous condition as it can originate from different parts of the pituitary gland, can be caused by different pathophysiological processes, and can be isolated or the manifestation of a underlying systemic disease. Hypophysitis usually presents with endocrine deficiencies, including diabetes insipidus, with varying patterns. A subset of patients presents with mass effects. The last decades major progress has been made in the understanding of this disease. New forms are now recognized, new diagnostics are being developed, and specific treatments are proposed. This review provides an overview of the current knowledge on hypophysitis using an aetiology-based approach and provides the clinician with a stepwise approach to the patient with (suspected) hypophysitis.

A case of langerhans cell histiocytosis of the mandible that spontaneously regressed after biopsy in a child

In younger patients of LCH, we should consider that the effectiveness of follow-up without aggressive treatment for SS-type LCH in the oral and maxillofacial bone. However, there are very rare case in which an SS-type LCH recurred after showing a healing tendency. Regular follow-up must be performed even after healing.

[Clinical and morphological analysis of Langerhans cell histiocytosis in a child of early age]

The authors characterize a rare variant of Langerhans cell histiocytosis in a child of early age. Multiple-system form including liver damage is characterized by a particularly severe course, especially in early childhood. The authors report clinical, morphological and immunohistochemical data of the patient aged 1 year and 11 months. It is shown that timely diagnosis of this disease should be carried out in close cooperation of surgeons and morphologists.

Isolated vulvar Langerhans cell histiocytosis

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Primary vulvar Langerhans cell histiocytosis is rare with less than 40 reported cases.

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Diagnosis of vulvar LCH requires prompt metastatic workup to rule out multisystem involvement.

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Treatment protocols for isolated vulvar LCH vary widely and there is not an established standard of care.

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Continue surveillance is warranted even after prolonged periods of remission.

Findings encountered in percutaneous cholangiography in a case of post-transplant recurrence of hepatic Langerhans cell histiocytosis with biliary involvement

This case report describes a four-year-old boy who presented with the diagnosis of LCH with liver involvement. This required a living-related liver transplant one year later. The primary disease recurred in the transplanted liver 6 months post-transplant and led to progressive biliary dilatation. A percutaneous trans-hepatic cholangiogram was performed five years after transplant, showing a pattern of multifocal biliary duct strictures mimicking the pattern of primary sclerosing cholangitis and a stenosis of the biliary-enteric anastomosis. Despite management with an internal-external biliary drain, the stenosis of the biliary-enteric anastomosis evolved to an occlusion one year after drain removal. This was associated with progression of the changes in the biliary tree, this time associated with significant saccular dilatations secondary to the multiple areas of stenosis. Due to these findings and progressive deterioration of the function of the graft, the patient required re-transplantation. This report illustrates the findings in imaging of the biliary tree secondary to the recurrence of LCH after liver transplantation, which may help to recognize this complication to physicians facing a similar clinical scenario.

Expression of CD1 molecules and colony-stimulating factor 1 receptor in indeterminate cell histiocytosis

Indeterminate cell histiocytosis (ICH) and Langerhans cell histiocytosis (LCH) are rare histiocyte proliferating disorders with unknown etiologies. However, both tumor cells immunophenotypically share some features of Langerhans cells (LC), thereby expressing CD1a. Recent transcriptome analysis revealed that circulating CD1c⁺ myeloid dendritic cells are the potential precursor of LCH tumor cells. LC express CD1a as well as CD1c, but not CD1b. We discovered that both tumor cells express CD1c, but not CD1b, similar to LC. Moreover, like LC, both tumor cells express colony-stimulating factor 1 receptor (CSF-1R). Considering the crucial role of the interleukin (IL)-34/CSF-1R axis for the development and survival of LC, CSF-1R on both tumor cells might facilitate their survival and proliferation in situ. These data provide additional evidence to support the fact that ICH and LCH share immunophenotypical features with LC. In addition, we hypothesized that tumor cells in ICH and LCH survive and proliferate through IL-34-mediated CSF-1R signaling.

A mutation in POLR3E impairs antiviral immune response and RNA polymerase III

RNA polymerase (Pol) III has a noncanonical role of viral DNA sensing in the innate immune system. This polymerase transcribes viral genomes to produce RNAs that lead to induction of type I interferons (IFNs). However, the genetic and functional links of Pol III to innate immunity in humans remain largely unknown. Here, we describe a rare homozygous mutation (D40H) in the POLR3E gene, coding for a protein subunit of Pol III, in a child with recurrent and systemic viral infections and Langerhans cell histiocytosis. Fibroblasts derived from the patient exhibit impaired induction of type I IFN and increased susceptibility to human cytomegalovirus (HCMV) infection. Cultured cell lines infected with HCMV show induction of POLR3E expression. However, induction is not restricted to DNA virus, as sindbis virus, an RNA virus, enhances the expression of this protein. Likewise, foreign nonviral DNA elevates the steady-state level of POLR3E and elicits promoter-dependent and -independent transcription by Pol III. Remarkably, the molecular mechanism underlying the D40H mutation of POLR3E involves the assembly of defective initiation complexes of Pol III. Our study links mutated POLR3E and Pol III to an innate immune deficiency state in humans.

Off-label uses of denosumab in metabolic bone diseases

Denosumab (Dmab), a monoclonal antibody against the receptor activator of nuclear factor-κB (RANK) ligand (RANKL) which substantially suppresses osteoclast activity, has been approved for the treatment of common metabolic bone diseases, including postmenopausal osteoporosis, male osteoporosis, and glucocorticoid-induced osteoporosis, in which the pathway of the RANK/RANKL/osteoprotegerin is dysregulated. However, the imbalance of RANKL/RANK/osteoprotegerin is also implicated in the pathogenesis of several other rare metabolic bone diseases, including Juvenile Paget disease, fibrous dysplasia, Hajdu Cheney syndrome and Langerhans cell histiocytosis, thus rendering Dmab a potential treatment option for these diseases. Dmab has been also administered off-label in selected patients (e.g., with Paget's disease, osteogenesis imperfecta, aneurysmal bone cysts) due to contraindications or unresponsiveness to standard treatment, such as bisphosphonates. Moreover, Dmab was administered to improve hypercalcemia induced by various diseases, including primary hyperparathyroidism, tuberculosis and immobilization. The aim of this review is to summarize existing evidence on off-label uses of Dmab in metabolic bone diseases and provide opinion for or against its use, which should be always considered on an individual basis.

Langerhans cell histiocytosis in an adult patient

Aim: to present a clinical case of a rare dermatosis — Langerhans cell histiocytosis (LCH) in an adult patient.

Materials and methods. A clinical and laboratory examination of a 64-year-old woman who had complained of rashes on the skin of the scalp, neck, trunk and lower extremities accompanied by itching was carried out. A histological study of skin biopsy samples from the lesion area, as well as an immunohistochemical study of Langerhans cell markers — langerin and S-100 protein — were performed.

Results. Clinical manifestations of the disease, the presence of histiocytic infiltrate in the epidermis and dermis during the histological study and immunohistochemical detection of langerin infiltrate cells and S-100 protein were all consistent with the diagnosis of LCH. The therapy with methotrexate subcutaneously significantly improved the patient’s condition.

Conclusion. Verification of the LCH diagnosis requires a histological study of skin biopsy samples and an immunohistochemical study of Langerhans cell markers. The efficacy of methotrexate in the treatment of this disease has been confirmed.

Eruptive Junctional Nevi Appearing During Langerhans Cell Histiocytosis Treatment

Langerhans cell histiocytosis (LCH) is a multisystemic disorder that results from the clonal proliferation of immunophenotypically and functionally immature Langerhans cells (LC). The detection of the V600E mutation in the BRAF oncogene in LCH biopsy specimens supports previous evidence that LCH is a neoplastic disorder. This mutation is present in other cutaneous lesions including malignant melanoma and benign nevi. Single case reports of a correlation between LCH and the appearance of eruptive nevi limited to the inguinal folds after chemotherapy have previously been described in the literature. This suggested that LCH could be an additional cause of eruptive melanocytic nevi, with a specific distribution mimicking that of LCH cutaneous lesions. We present the case of a 6-year-old boy, previously treated with chemotherapy for Langerhans cell histiocytosis, with disseminated junctional nevi. Although this co-occurrence may be coincidental, the skin involvement is distinct from other previously reported clinical cases. It would be interesting to evaluate whether the BRAF mutation described in LCH cells might in fact support a genetic background for the development of nevi in these patients.

Langerhans cell histiocytosis of the jaw, a mimicker of osteomyelitis on CT and MR images: A retrospective analysis

Differential diagnosis of Langerhans Cell Histiocytosis (LCH) in the jaw is essential for early treatment including systemic therapy. Records of 17 patients (6 men and 11 women; mean age, 14 years) with histologically confirmed LCH were reviewed. All the lesions occurred in the mandible. Most of the cases (n=12) were intraosseous type LCH, only 5 patients had alveolar type LCH. Patients complained of facial swelling and pain most likely. In the 14 patients who underwent CT and/or MR imaging, all LCH lesions were osteolytic, with a mean size of 23 mm. LCH presented as expansile lesions with periosteal new bone formation, perilesional sclerosis, fluid attenuation/signal within the lesion, and inflammatory changes in adjacent soft tissues on CT/MR images. Considering the major symptoms of LCH were swelling and pain, the differential diagnosis of LCH from osteomyelitis might be more difficult. The differential diagnosis for osteolytic lesions of the jaw with surrounding inflammatory changes should include LCH, especially in young patients.

High Prevalence of BRAF V600E Mutations in Langerhans Cell Histiocytosis of Head and Neck in Chinese Patients

Langerhans cell histiocytosis (LCH) is characterized by clonal proliferation of Langerhans cells and has been classified as a hematolymphoid tumor. BRAF V600E mutation was found to be frequent in LCH; however, it has also been reported that Asia patients with LCH tend to show a lower rate of BRAF V600E mutation. In this study, we found LCH from the head and neck region often involved bone especially the posterior of the mandible and presented a high prevalence of BRAF V600E mutation in Chinese patients. Our findings also showed immunohistochemical detection correlated very well to DNA sequencing of BRAF alterations, which may be useful in the diagnosis of LCH, especially in cases with a low proportion of Langerhans cells, and BRAF inhibitors might be a treatment option for patients with LCH harboring BRAF V600E mutation.

Practical Applications in Immunohistochemistry: An Immunophenotypic Approach to the Spleen

CONTEXT.—

Even though immunohistochemistry is routinely used by pathologists, evaluation of immunohistochemistry in splenic lesions remains difficult for many. Classification of benign and splenic lesions often requires a combination of hematoxylin-eosin evaluation, immunophenotyping, and sometimes molecular testing. Immunohistochemical staining is essential in evaluating many splenic lesions, and requires an understanding of the normal compartments of the spleen.

OBJECTIVE.—

To address different immunohistochemical features used for identification and subclassification of different lesions of the spleen, as well as in the normal compartments of the spleen.

DATA SOURCES.—

The information outlined in this review article is based on our experiences with a variety of spleen cases, on the current World Health Organization classification of hematopoietic and lymphoid tumors, and on a review of English-language articles published during 2018.

CONCLUSIONS.—

Features for phenotyping normal spleen as well as a variety of splenic lesions, including littoral cell angioma and splenic marginal zone lymphoma, are discussed. Suggested immunopanels are provided to assist in the diagnosis of different lesions of the spleen.

Radiotherapy for Langerhans cell histiocytosis with paraplegia: A rare oncologic emergency case report in infancy and literature review

BACKGROUND

Langerhans cell histiocytosis (LCH) is a clonal disease with focal or disseminated lesions that may compress the surrounding tissues, including the spinal cord. Because few reports have described the spinal symptoms as the first manifestation of pediatric LCH, the long-term neurological outcomes remain unclear.

CASE REPORT AND LITERATURE REVIEW

We report a 21-month-old boy who presented with sudden-onset paraplegia. Imaging analyses revealed that osteolytic lesions and epidural tumors compressing the spinal cord at the T7-9 vertebrae. Twelve days after he developed leg weakness, emergency radiotherapy was started after a tumor biopsy. During the course of radiotherapy, paralysis steadily ameliorated. After we excluded infections and determined the pathological diagnosis of LCH, multi-drug chemotherapy was started. Apparent improvement in his complete paraplegia was observed after a total 15 Gy of radiotherapy and subsequent chemotherapy, leaving no neurological sequelae at 4 years of age. Through a literature search of studies published from 1980 to 2017, we found that children with LCH showed a generally favorable recovery from neurological dysfunction after the acute phase of spinal symptoms.

CONCLUSION

This report underscores the utility of emergency radiotherapy for the neurological recovery of spinal LCH in infants. Our long-term observation further denotes the value of this treatment in terms of the intact survival with preserved motor functions and physical growth.

Cladribine treatment for Erdheim-Chester disease involving the central nervous system and concomitant polycythemia vera: A case report

Erdheim–Chester disease (ECD), a rare form of non-Langerhans cell histiocytosis, is characterized by the infiltration of foamy CD68⁺ and CD1a^- histiocytes into multiple organ systems. Central nervous system (CNS) involvement has recently been reported to be a poor prognostic factor when treating ECD with interferon alpha. We report the case of a 66-year-old Japanese patient with ECD involving the CNS who harbored the BRAF V600E mutation and also concomitantly developed polycythemia vera with the JAK2 V617F mutation. We confirmed 2-chlorodeoxyadenosine (cladribine) therapy to be effective for the patient in this case.

JAG2 signaling induces differentiation of CD14+ monocytes into Langerhans cell histiocytosis-like cells

Langerhans cell histiocytosis (LCH) is a MAPK pathway-driven disease characterized by the accumulation of CD1a⁺ langerin⁺ cells of unknown origin. We have previously reported that the Notch signaling pathway is active in LCH lesions and that the Notch ligand Jagged2 (JAG2) induces CD1a and langerin expression in monocytes in vitro. Here we show that Notch signaling induces monocytes to acquire an LCH gene signature and that Notch inhibition suppresses the LCH phenotype. In contrast, while also CD1c⁺ dendritic cells or IL-4-stimulated CD14⁺ monocytes acquire CD1a and langerin positivity in culture, their gene expression profiles and surface phenotypes are more different from primary LCH cells. We propose a model where CD14⁺ monocytes serve as LCH cell precursor and JAG2-mediated activation of the Notch signaling pathway initiates a differentiation of monocytes toward LCH cells in selected niches and thereby contributes to LCH pathogenesis.

Bone metabolism in Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a rare disease of not well-defined etiology that involves immune cell activation and frequently affects the skeleton. Bone involvement in LCH usually presents in the form of osteolytic lesions along with low bone mineral density. Various molecules involved in bone metabolism are implicated in the pathogenesis of LCH or may be affected during the course of the disease, including interleukins (ILs), tumor necrosis factor α, receptor activator of NF-κB (RANK) and its soluble ligand RANKL, osteoprotegerin (OPG), periostin and sclerostin. Among them IL-17A, periostin and RANKL have been proposed as potential serum biomarkers for LCH, particularly as the interaction between RANK, RANKL and OPG not only regulates bone homeostasis through its effects on the osteoclasts but also affects the activation and survival of immune cells. Significant changes in circulating and lesional RANKL levels have been observed in LCH patients irrespective of bone involvement. Standard LCH management includes local or systematic administration of corticosteroids and chemotherapy. Given the implication of RANK, RANKL and OPG in the pathogenesis of the disease and the osteolytic nature of bone lesions, agents aiming at inhibiting the RANKL pathway and/or osteoclastic activation, such as bisphosphonates and denosumab, may have a role in the therapeutic approach of LCH although further clinical investigation is warranted.

Endocrine and metabolic assessment in adults with Langerhans cell histiocytosis

CONTEXT

Diabetes insipidus (DI) is one of most common complications of Langerhans cell histiocytosis (LCH) but prevalence of anterior pituitary deficiencies and metabolic alterations have not been clearly defined yet.

OBJECTIVES

Evaluate prevalence of endocrine and metabolic manifestations in a cohort of patients affected by Pulmonary LCH.

METHODS

Observational cross-sectional study on 18 adults (7 M/11 F, 42±12years) studied for complete basal and dynamic endocrine lab tests and glucose metabolism.

RESULTS

Hypothalamic-pituitary endocrine alterations were found in 9 patients: 9 had DI, 5 Growth Hormone Deficiency (GHD), 5 central hypogonadism, 3 central hypothyroidism and 1 central hypoadrenalism. Hyperprolactinemia and hypothalamic syndrome were found in 2 patients each. All these central endocrine alterations were always associated to DI. Five of the 10 MRI performed showed abnormalities. Prevalence of obesity and glucose alterations (either DM or IFG/IGT) were respectively 39% and 33%, higher than expected basing on epidemiological data on general Italian population. Multi-system-LCH without risk-organ involvement (LCH MS-RO^-) seems to have slightly higher prevalence of insulin resistance, glucose alterations and metabolic syndrome than LCH with isolated lung involvement (LCH SS lung⁺). A papillary BRAFV600E positive thyroid carcinoma was diagnosed in one patient.

CONCLUSIONS

The presence of anterior pituitary deficiencies should be systematically sought in all LCH patients with DI both at diagnosis and during the follow-up by basal and dynamic hormonal assessment. Patients with pulmonary LCH, particularly those with MS disease, have a worse metabolic profile than general population. Occurrence of papillary thyroid carcinoma has been reported.

[BRAF-V600E mutation and its clinical significance in children with Langerhans cell histiocytosis]

OBJECTIVE

To investigate the clinical significance of BRAF-V600E mutation in children with Langerhans cell histiocytosis (LCH).

METHODS

Real-time fluorescence quantitative PCR was used to detect BRAF-V600E mutation in paraffin-embedded tissue samples from 26 children with LCH. A retrospective analysis was performed for the association of BRAF-V600E mutation with clinical features and prognosis of children with LCH.

RESULTS

Of the 26 children, 25 received standard chemotherapy, with a 2-year overall survival (OS) rate of 100% and a 2-year event-free survival (EFS) rate of 88%. Of the 26 pathological samples, 18 (70%) came from bone tissue, and the positive rate of BRAF-V600E mutation reached 50% (13/26). The positive rate of BRAF-V600E gene mutation was not associated with age, sex, affected organ, clinical classification, early treatment response, recurrence, and 2-year OS and EFS rates of the children with LCH (P&gt;0.05), but it was associated with clinical grouping of LCH (P&lt;0.05).

CONCLUSIONS

Children with LCH tend to have a high OS rate and a high incidence rate of BRAF-V600E mutation. BRAF-V600E mutation is associated with clinical grouping of LCH.

The application of x-ray, computed tomography, and magnetic resonance imaging on 22 pediatric Langerhans cell histiocytosis patients with long bone involvement: A retrospective analysis

The studies focusing on x-ray, computed tomography (CT), and magnetic resonance imaging (MRI) in pediatric Langerhans cell histiocytosis (LCH) patients were still rare. Therefore, we aimed to evaluate the application of x-ray, CT, and MRI in pediatric LCH patients with long bone involvement.Total 22 pediatric LCH patients were included in this study. The diagnosis of LCH was confirmed by pathological examination. All patients were followed up for 3 years. X-ray, CT, or MRI was performed and the results were recorded for further analyses.Among 22 pediatric patients, x-ray (n = 20), CT (n = 18), or MRI (n = 12) were used to scan the lesion on long bones affected by LCH. Femurs (n = 13, 38.24%), tibia (n = 11, 32.35%), humerus (n = 5, 14.71%), and radius (n = 4, 11.76%) were the most frequently affected anatomic sites. Ovoid or round radiolucent lesions, aggressive periosteal reaction, and swelling of surrounding soft tissues were characteristic image of long bones on x-ray, CT, and MRI in pediatric LCH.Femurs, tibia, humerus, and radius were the most commonly affected long bones of pediatric LCH. The application of x-ray, CT, and MRI on long bones could help with the diagnosis of pediatric LCH.

Cutaneous Hematolymphoid and Histiocytic Proliferations in Children

This article focuses on cutaneous hematopoietic neoplasms that are more likely to be encountered in the pediatric age-group and includes both lymphoproliferative and histiocytic disorders. The cutaneous hematologic disorders in children have a different epidemiologic profile to what is seen during adulthood. Although mycosis fungoides is the most frequent form of cutaneous lymphoma in adults, it is very rare in children. Because lymphoblastic leukemias and lymphomas are more frequent in the pediatric setting, cutaneous leukemic infiltrates are relatively common in this age-group. Similarly, histiocytic disorders are more common in children, particularly Langerhans cell histiocytosis and juvenile xanthogranuloma. Notably, the histiocytic disorders have undergone significant modifications on their nomenclature in the basis of the molecular characteristics that are present in them. A summary of the most frequent cutaneous hematopoietic disorders in children will be discussed further in this review.

The multiple faces of Langerhans cell histiocytosis in childhood: A gentle reminder

Langerhans cell histiocytosis (LCH) is a rare hematologic disorder that results from the clonal multiplication and accumulation of immature dendritic Langerhans cells. Its reported incidence rate varies, but is considered to be 2.6-8.9 per million children who are <15 years of age each year. It may affect any system or organ. The present study reported 4 pediatric LCH cases in order to highlight the heterogeneity of the initial presentation, and the pitfalls that may mislead clinicians and delay diagnosis. The clinical features, as well as the pathognomonic imaging, pathology findings and treatment options were presented. LCH may be rare, but it should always be included in the differential diagnosis of persistent eczema, unexplained skin lesions, diabetes insipidus and persistent bone pain, among others. While the debate on pathogenesis and treatment is ongoing, high index of suspicion among pediatricians, pediatric oncologists and other specialists (pathologists, dermatologists, orthopaedic surgeons, general practitioners or family physicians) is essential for early diagnosis, and optimal outcome.

Histiocytic lesions of the orbit: A study of 9 cases

PURPOSE

To describe the clinical presentation, treatment, and outcome of patients with histiocytic lesions of the orbit.

METHODS

Retrospective study of 9 patients treated and followed up between October 2001 and January 2018.

RESULTS

Eight patients in our series were males and one patient was female. The mean age at presentation was 16.8 years (range, 1 to 42 years). All patients had unilateral disease. The most common presenting complaint was upper eyelid swelling in 8 of 9. All patients underwent preoperative computed tomography (CT) and magnetic resonance imaging (MRI). Eight of 9 patients demonstrated orbital bone erosion with adjacent soft tissue mass. Destruction of the orbital roof and contrast enhancement of dura were detected in 3 cases. All cases underwent orbitotomy and subtotal tumor excision with additional bone curettage (4 cases) and intraorbital steroid (40 mg triamcinolone acetonide) injection (3 cases). Adjuvant systemic chemotherapy consisting of vinblastine and prednisone was administered in 3 cases with dural involvement. External radiotherapy (1000 cGy) was applied in one case because of widespread disease. Histopathologic diagnoses were eosinophilic granuloma (7 cases), necrotic xanthogranuloma (1 case), and Langerhans cell sarcoma (1 case). The mean follow-up period after diagnosis was 19.7 months (range, 1-96 months). There was no systemic or multifocal bone involvement in eosinophilic granuloma cases at initial presentation and follow-up. None of these patients developed diabetes insipidus or neurologic symptoms. The patient with Langerhans cell sarcoma died from systemic disease 1 month after diagnosis of the orbital tumor. The patient with necrotic xanthogranuloma did not develop any malignancy at 9 months follow-up.

CONCLUSIONS

Eosinophilic granuloma was the most frequently encountered orbital histiocytic lesion in our series. Eosiophilic granuloma usually responded well to subtotal tumor excision, bone curettage, and intraorbital corticosteroid injections. Systemic chemotherapy was used in cases with full thickness bone destruction and adjacent dural enhancement in an effort to prevent the development of central nervous system disease.

CD207+CD1a+ cells circulate in pediatric patients with active Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a rare disease with an unknown etiology characterized by heterogeneous lesions containing CD207⁺CD1a⁺ cells that can arise in almost any tissue and cause significant morbidity and mortality. Precursors of pathological Langerhans cells have yet to be defined. Our aim was to identify circulating CD207⁺CD1a⁺ cells and their inducers in LCH. Expression of CD207 and CD1a in the blood myeloid compartment as well as thymic stromal lymphopoietin (TSLP) and transforming growth factor β (TGF-β) plasma levels were measured in 22 pediatric patients with active disease (AD) or nonactive disease (NAD). In patients with AD vs those with NAD, the myeloid compartment showed an increased CD11b (CD11b^high plus CD11b⁺) fraction (39.7 ± 3.6 vs 18.6 ± 1.9), a higher percentage of circulating CD11b^highCD11c⁺CD207⁺ cells (44.5 ± 11.3 vs 3.2 ± 0.5), and the presence of CD11c^highCD207⁺CD1a⁺ cells (25.0 ± 9.1 vs 2.3 ± 0.5). Blood CD207⁺CD1a⁺ cells were not observed in adult controls or umbilical cord. Increased TSLP and TGF-β levels were detected in patients with AD. Interestingly, plasma from patients with AD induces CD207 expression on CD14⁺ monocytes. We conclude that CD207⁺CD1a⁺ cells are circulating in patients with active LCH, and TSLP and TGF-β are potential drivers of Langerhans-like cells in vivo.

Langerhans cell histiocytosis limited to the female genital tract: A review of literature with three additional cases

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LCH of the female reproductive tract has four patterns of involvement.

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A comprehensive literature review revealed 35 cases of pure genital LCH.

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We report two new cases of pure LCH lesions of the vulva and one of the cervix.

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Treatment of LCH varies and there is no standard for pure genital involvement.

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Prognosis of LCH confined to the gynecologic tract appears to be favorable.

Langerhans cell histiocytosis of the maxillae in a child treated only with chemotherapy: a case report

Background

Langerhans cell histiocytosis is a sporadic disease caused by an uncontrolled pathogenic clonal proliferation of dendritic cells that have Langerhans cell characteristics. New treatment protocols provided by the HISTSOC-LCH-III (NCT00276757) trial show an improvement in the survival of children with langerhans cell histiocytosis.

Case presentation

We report a case of Langerhans cell histiocytosis, which presented as an osteolytic lesion of the left pre-maxillae enclosing the deciduous incisor and canine in a 7-month-old white Italian boy. He was treated with chemotherapy. He achieved complete remission after 7 months and after 24 months no signs of recurrence were observed.

Conclusions

As a result of this treatment, anesthetic sequelae and loss of teeth were avoided; in addition, we prevented a loss of the vertical dimension of occlusion.

Langerhans cell histiocytosis: Skin diseases and visceral lesions

Langerhans cell histiocytosis (LCH) is a rare clonal proliferative disorder that belongs to class I histiocytoses and is characterized by infiltration of one or many organs by Langerhans cells to form granulomas. The literature analysis could identify a lot of etiological, pathogenetic, and trigger factors and mechanisms for LCH development, which determine the diversity of the clinical picture and course of the disease. The clinical manifestations of LCH are very variable and depend on the severity of lesions and the age of patients. In addition to skin lesions, there is involvement of one or more visceral organs. Difficulties in diagnosing the disease lead to statistical variations of LCH in different countries of the world and require more attention by physicians of all specialties.

Denosumab for the treatment of adult multisystem Langerhans cell histiocytosis

PURPOSE

An etiological treatment is currently lacking for Langerhans Cell Histiocytosis (LCH). Receptor activator of nuclear factor κB ligand (RANKL) appears to play a central role in the lesional immunological process inducing compensatory osteoprotegerin (OPG) activation. In a preliminary study we aimed to evaluate for the first time the use of denosumab, a RANKL inhibitor, as a targeted treatment strategy in LCH in order to support and enhance endogenous OPG action in order to control or alter the lesional immunological process.

PROCEDURES

Two adult female patients with painful osteolytic bone lesions and concomitant pulmonary involvement received bimonthly denosumab 120mg in a total of 4 doses.

RESULTS

Both patients reported an immediate pain relief within the first two weeks following the 1st dose of denosumab. One month following the last dose an almost full remission of the initial osteolytic and lung lesions was observed, although an apparent new bone lesion was detected in one patient that was treated with a single intralesional steroid injection. No adverse events were recorded throughout the treatment period. Both patients have no active disease 6months following the last denosumab dose.

CONCLUSIONS

Denosumab could be considered an effective treatment option in adults with multisystem LCH also exerting a significant analgesic effect in bone lesions, warranting further investigation.

The use of BRAF V600E mutation-specific immunohistochemistry in pediatric Langerhans cell histiocytosis

BRAF p.V600E mutations are detected in greater than 50% of pediatric Langerhans cell histiocytosis (LCH) lesions. However, the use of mutation-specific BRAF V600E immunohistochemistry (IHC) as a surrogate for molecular testing in pediatric LCH is unknown. We tested the mutation-specific BRAF V600E monoclonal antibody (clone VE1) in formalin-fixed, paraffin-embedded LCH samples from 26 pediatric patients (14 males and 12 females, ages 7 mo-17 y) using allele-specific real-time polymerase chain reaction (PCR) with a limit of detection of 0.5% as the comparative gold standard. BRAF VE1 staining was scored for both intensity (0-3+) and percentage of immunoreactive tumor cells (0%-100%). BRAF VE1 immunoreactivity was determined using both lenient (≥1+, ≥1%) and stringent (≥2+, ≥10%) scoring criteria. Using lenient-scoring criteria, we found that the sensitivity and specificity of IHC compared with allele-specific real-time PCR were 100.0% and 18.2%, respectively. The poor specificity of lenient IHC analysis was attributable to weak, 1+ staining in both BRAF-mutated and wild-type LCH. Using stringent-scoring criteria, we found that specificity improved to 100.0% at the expense of sensitivity that decreased to 80.0%. Stringent scoring generated 3 false-negative results, but in all cases, neoplastic tissue comprised less than 5% of the stained section and/or the specimen was decalcified. In conclusion, highly sensitive molecular assays remain the gold standard for BRAF mutation analysis in LCH paraffin-embedded lesions. To avoid false-positive results, unequivocal VE1 staining of 2+ intensity in greater than or equal to 10% neoplastic histiocytes is required. However, negative VE1 results require additional studies to exclude false-negatives, and stringent-scoring criteria may not be optimal for scant or decalcified specimens.