Treatment of Langerhans cell histiocytosis: role of BRAF/MAPK inhibition

Pediatric diencephalic tumors: a constellation of entities and management modalities

The diencephalon is a complex midline structure consisting of the hypothalamus, neurohypophysis, subthalamus, thalamus, epithalamus, and pineal body. Tumors arising from each of these diencephalic components differ significantly in terms of biology and prognosis. The aim of this comprehensive review is to describe the epidemiology, clinical symptoms, imaging, histology, and molecular markers in the context of the 2021 WHO classification of central nervous system neoplasms. We will also discuss the current management of each of these tumors.

Expression and Clinical Correlation of PD-1/PD-L1 and VE1(BRAFp.V600E) in Pediatric Langerhans Cell Histiocytosis

Background And Objectives

Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasm with a wide spectrum of clinical presentations. Programmed Cell Death-1 (PD-1) receptor and its ligand (PD-L1) are overexpressed in LCH, but their clinical significance is unknown. We performed a clinical correlation study of PD-1/PD-L1 and VE1(BRAFp.V600E) expression in 131 children with LCH.

Methods

A total of 111 samples were tested for PD-1/PD-L1 and 109 for VE1(BRAFp.V600E) mutant protein by immunohistochemistry.

Results

PD-1, PD-L1 and VE1(BRAFp.V600E) positivity was observed in 40.5%, 31.53% and 55%, respectively. PD-1/ PD-L1 expression showed no significant effect on the rate of disease reactivations, early response to therapy or late sequelae. The 5-year EFS was not statistically different between patients with PD-1 positive compared to those with PD-1 negative tumours (47.7% vs.58.8%, p=0.17). Similar 5-year EFS rates were also seen in those who were PD-L1 positive compared to PD-L1 negative cases (50.5% vs.55.5%, p=0.61). VE1(BRAFp.V600E) positivity was associated with a significantly higher frequency of risk-organ involvement (p=0.0053), but no significant effect on early response to therapy or rates of reactivations or late sequelae.

Conclusions

Our study showed no significant correlation between VE1(BRAFp.V600E) expression, PD-1 and PD-L1 and clinical outcome in pediatric LCH.

Langerhans Cells-Revising Their Role in Skin Pathologies

Langerhans cells (LCs) constitute a cellular immune network across the epidermis. Because they are located at the skin barrier, they are considered immune sentinels of the skin. These antigen-presenting cells are capable of migrating to skin draining lymph nodes to prime adaptive immune cells, namely T- and B-lymphocytes, which will ultimately lead to a broad range of immune responses. Moreover, LCs have been shown to possess important roles in the anti-cancer immune responses. Indeed, the literature nicely highlights the role of LCs in melanoma. In line with this, LCs have been found in melanoma tissues where they contribute to the local immune response. Moreover, the immunogenic properties of LCs render them attractive targets for designing vaccines to treat melanoma and autoimmune diseases. Overall, future studies will help to enlarge the portfolio of immune properties of LCs, and aid the prognosis and development of novel therapeutic approaches to treating skin pathologies, including cancers.

Surveillance of Isolated Colonic Langerhans Cell Histiocytosis in an Adult: A Case Report

Langerhans cell histiocytosis (LCH) is a rare disorder involving the proliferation of myeloid-derived dendritic cells. It most commonly affects children aged less than 1 to 2 years old. Langerhans cell histiocytosis in adults is more uncommon with an estimated incidence of 1 to 2 cases per 1 million. Langerhans cell histiocytosis can present as a multisystem or single-system disease involving bone, skin, lymph nodes, and various other organ systems. The spectrum of symptoms can range from asymptomatic disease, localized skeletal or dermatologic manifestations, or systemic symptoms of weight loss, fever, and other organ-specific manifestations. Langerhans cell histiocytosis with isolated involvement of the gastrointestinal tract is exceedingly rare with only approximately 14 cases reported in the English medical literature. Here, we report an additional case of LCH presenting as an isolated colonic polyp. This patient was also followed for a 3-year period after initial diagnosis to provide valuable follow-up data. With this case, we aim to contribute to the literature by further characterizing the presentation, treatment, and disease course of this rare phenomenon and provide valuable data to guide future screening guidelines for isolated LCH polyps in the colon.

Current perspectives on the role of liver transplantation for Langerhans cell histiocytosis: A narrative review

Langerhans cell histiocytosis (LCH) is a malignant disease of the histiocytes involving various organ systems. The spectrum of liver involvement in LCH ranges from mild transaminitis to end-stage liver disease. The hallmark of hepatic LCH is secondary sclerosing cholangitis, which manifests due to a progressive destruction of the biliary tree by malignant histiocytes. Chemotherapy remains the mainstay of treatment for active LCH. Early recognition, diagnosis and a systematic approach to the management of LCH can ameliorate the disease process. Nonetheless, the liver involvement in these patients may progress despite the LCH being in remission. Liver transplantation (LT) remains central in the management of such patients. Various facets of the management of LCH, especially those with liver involvement remain unclear. Furthermore, aspects of LT in LCH with regards to the indication, timing and post-LT management, including immunosuppression and adjuvant therapy, remain undefined. This review summarises the current evidence and discusses the practical aspects of the role of LT in the management of LCH.

Results of TETimaX Trial of Langerhans Cell Histiocytosis Treatment and Perspectives on the Role of Imatinib Mesylate in the Era of MAPK Signaling

Langerhans cell histiocytosis (LCH) is a rare disease that has a variable clinical presentation and unpredictable behavior. Until recently, therapeutic options were limited. Insights into the role of mitogen-activated protein kinase (MAPK) signaling have allowed the increased use of targeted treatments. Before the advent of drugs that interfere with this pathway, investigations concerning the tyrosine kinase inhibitor imatinib opened the way to a rationale-based therapeutic approach to the disease. Imatinib block the binding site of ATP in the BCR/ABL protein and is also a platelet-derived growth factor receptor (PDGFR) and a KIT (CD117) kinase inhibitor. A case of refractory LCH with brain involvement was reported to be successfully treated with imatinib. Thereafter, we further explored the role of this tyrosine kinase inhibitor. The present study is composed of an immunohistochemical evaluation of PDGFRβ expression and a clinical evaluation of imatinib in a series of LCH patients. In the first part, a series of 10 samples obtained from LCH patients was examined and a strong immunohistochemistry expression of PDGFRβ was found in 40% of the cases. In the clinical part of the study, five patients were enrolled. Long-lasting disease control was obtained. These results may suggest a potential role for this drug in the current age.

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.

A study of pathological characteristics and BRAF V600E status in Langerhans cell histiocytosis of Vietnamese children

Background

Langerhans cell histiocytosis (LCH) is more common in children than adults and involves many organs. In children, the BRAF V600E mutation is associated with recurrent and high-risk LCH.

Methods

We collected paraffin blocks of 94 pediatric LCH patients to detect BRAF_V600E mutation by sequencing. The relationship between BRAF V600E status and clinicopathological parameters were also critically analyzed.

Results

BRAF V600E mutation exon 15 was detected in 45 cases (47.9%). Multiple systems LCH showed a significantly higher BRAF_V600E mutation rate than a single system (p=.001). No statistical significance was evident for other clinical characteristics such as age, sex, location, risk organs involvement, and CD1a expression.

Conclusions

In Vietnamese LCH children, the proportion of BRAF V600E mutational status was relatively high and related to multiple systems.

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.

Adult pulmonary Langerhans cell histiocytosis revealed by central diabetes insipidus: A case report and literature review

Langerhans cell histiocytosis (LCH) is a rare systemic and heterogeneous disease secondary to proliferation and diffuse infiltration of immature CD1a-positive dendritic cells, also known as Langerhans cells. LCH affects predominantly paediatric patients and is rarely diagnosed in adulthood. Despite its worldwide prevalence, most reported cases are found in the Japanese population. There is no consensus regarding treatment strategy due to the low incidence of this disease and the diversity of symptoms that appear. An integrative literature review was conducted based on the PubMed database using MeSH terms 'Langerhans', 'histiocytosis' and 'adult'. The present report describes a case of a successfully treated LCH-induced central diabetes insipidus (uncommon presentation in adult patients) as well as an updated review of current evidence published on this matter.

Effectiveness and Safety of Dabrafenib in the Treatment of 20 Chinese Children with BRAFV600E-Mutated Langerhans Cell Histiocytosis

Purpose

We sought to investigate the effectiveness and safety of dabrafenib in children with BRAF^V600E-mutated Langerhans cell histiocytosis (LCH).

Materials and Methods

A retrospective analysis was performed on 20 children with BRAF^V600E-mutated LCH who were treated with dabrafenib.

Results

The median age at which the patients started taking dabrafenib was 2.3 years old (range, 0.6 to 6.5 years). The ratio of boys to girls was 2.3:1. The median follow-up time was 30.8 months (range, 18.9 to 43.6 months). There were 14 patients (70%) in the risk organ (RO)⁺ group and six patients (30%) in the RO⁻ group. All patients were initially treated with traditional chemotherapy and then shifted to targeted therapy due to poor control of LCH or intolerance to chemotherapy. The overall objective response rate and the overall disease control rate were 65% and 75%, respectively. During treatment, circulating levels of cell-free BRAF^V600E (cfBRAF^V600E) became negative in 60% of the patients within a median period of 3.0 months (range, 1.0 to 9.0 months). Grade 2 or 3 adverse effects occurred in five patients.

Conclusion

Some children with BRAF^V600E-mutated LCH may benefit from monotherapy with dabrafenib, especially high-risk patients with concomitant hemophagocytic lymphohistiocytosis and intolerance to chemotherapy. The safety of dabrafenib is notable. A prospective study with a larger sample size is required to determine the optimal dosage and treatment duration.

Necrotizing myositis in a rectus muscle arising in the setting of long-standing Langerhans cell histiocystosis and recent dabrafenib treatment

Purpose

to describe an unusual case of necrotizing myositis in a rectus muscle, possibly related to BRAF inhibitor therapy.

Observations

An 18-year old man with neurodegenerative Langerhans cell histiocytosis (LCH), recently started on the BRAF inhibitor dabrafenib, presented with right eye pain. Magnetic resonance imaging (MRI) orbits revealed a rectus muscle mass concerning for LCH recurrence or malignancy. Dabrafenib was stopped, and incisional biopsy of the mass was performed. The mass was absent on post-operative MRI, so no further treatment was pursued. Histopathologic evaluation was initially concerning for sarcoma, but on further analysis, appeared more consistent with necrotizing myositis. The mass did not recur, nor did the patient develop other signs or symptoms concerning for myositis or malignancy over a 24-month follow-up period.

Conclusions

Necrotizing myositis has not been previously described in a rectus muscle or with BRAF inhibitor use, though myalgias and malignancies are established side effects. Necrotizing myositis may masquerade as sarcoma and should be on the differential diagnosis for a new mass in the setting of dabrafenib therapy.

BRAF V600E-Positive Congenital Multisite Langerhans Cell Histiocytosis

Congenital Langerhans cell histiocytosis (LCH) usually manifests as a disease limited to the skin, with self-healing characteristics; however, in some cases, it may be a more severe entity, with multisystemic expression and poor prognosis. We present the case of a patient diagnosed with multisystemic congenital LCH, with the presence of the BRAF V600E mutation, with a severe form of the disease, with risk organ compromise, and manifestations of resistance to chemotherapy. This case is a challenge due to the disease's biologically aggressive behavior in this patient. It presents unique treatment difficulties as a result of inherent resistance to conventional therapy and uncertain response to BRAF inhibitors.

Multisystemic Pediatric Langerhans cell histiocytosis: a comprehensive clinico-pathological and BRAF V600E mutation study at autopsy

Langerhans cell histiocytosis (LCH), a disorder of antigen-presenting cells, is the commonest disorder of the mononuclear phagocytic system. Diagnosis is always challenging due to heterogeneous clinical presentation. However, with the evolution and better understanding of its biology, many of these children are being diagnosed early and offered appropriate therapy. Despite these advances, in developing countries, an early diagnosis is still challenging due to resource constraints for specialized tests. As a result, many patients succumb to their disease. Autopsy data on LCH is notably lacking in the literature. We sought to analyze the clinical (including mutational) and morphologic features at autopsy in six proven cases of LCH. This study includes a detailed clinico-pathological and mutational analysis of 6 proven cases of LCH. Presence of BRAF V600E mutation was assessed by both Real Time PCR and Sanger sequencing. A varied spectrum of organ involvement was noted with some rare and novel morphological findings, like nodular bronchiolocentric infiltration of LCH cells, lymphovascular emboli of LCH cells, and paucity of eosinophils within the infiltrate; these features have not been described earlier. Surprisingly, all cases were negative for BRAF V600E mutation on both RQ-PCR and Sanger sequencing. The present study is perhaps the first autopsy series on LCH. This extensive autopsy analysis represents a correlation of pathological features with clinical symptoms which provides clues for a timely diagnosis and appropriate therapeutic intervention. Also, our findings hint at the low frequency of BRAF V600E mutation in our LCH patients.

Extracellular signal-regulated kinase activation of self-healing Langerhans cell histiocytosis: A case report

A 3-month-old boy developed small papules on his trunk. After the papules increased in number, the patient was diagnosed with Langerhans cell histiocytosis based on the pathological findings. He was referred to our department for further examination. Upon initial examination, the papules and nodules were scattered on his back, abdomen and lumbar region. Because he did not present with any organ involvement except the skin, he was diagnosed with single-system and skin-limited Langerhans cell histiocytosis. Skin rashes were treated with a topical steroid and started regressing 3 months after onset. All papules disappeared 6 months after onset. In this boy, the Langerhans cell histiocytosis tumor cells expressed phosphorylated extracellular signal-regulated kinases. In Langerhans cell histiocytosis, BRAF V600E and other genes are known to mutate to act as driver mutations in stem cells of the myeloid dendritic cell lineage. Consequently, extracellular signal-regulated kinases are continuously activated, which contributes to Langerhans cell histiocytosis carcinogenesis.

Initial Symptoms of Langerhans Cell Histiocytosis: A Case Series

Langerhans cell histiocytosis (LCH) is a rare childhood hematopoietic disease, and hence, there are few reports summarizing the course leading to the diagnosis. We described the initial symptoms and the clinical course of LCH. We carried out a retrospective review of charts from a single medical center, and 21 patients with the diagnosis of LCH were enrolled. The initial symptoms of 16 cases were caused by bone lesions; of these cases, there were 8 instances of soft tissue swelling as the initial symptom (38%) and 8 instances of bone pain without swelling (38%). Among the cases of bone lesion, 4 of 6 cases of skull lesion were painless while all vertebral body lesions and long bone lesions were accompanied by pain. LCH bone lesions caused various symptoms depending on the site of the lesion and this makes the diagnosis difficult. A detailed physical examination and imaging studies are recommended for early diagnosis.

Imaging of Histiocytosis in the Era of Genomic Medicine

Histiocytosis describes a group of diseases that have long been considered enigmatic in the history of medicine. Recently, novel genomic analyses have identified somatic oncogenic driver mutations responsible for the pathogenesis of these entities. These discoveries have led to the recharacterization of histiocytoses as neoplastic diseases and have opened a new era of precision medicine approaches for treatment. The histiocytic disorders demonstrate a variety of imaging manifestations involving multiple organ systems, and radiologists play a major role in diagnosis and monitoring. An up-to-date knowledge of the novel genomic discoveries and their implications is essential for radiologists to understand the new approaches to treating histiocytic disorders and to contribute as key members of the multidisciplinary treatment team. This article provides a cutting-edge review of the novel concepts in histiocytosis, with a focus on recent genomic discoveries and precision medicine approaches to treating the disease, and describes imaging manifestations with correlative histologic and genomic findings, with an emphasis on adult-onset cases and uncommon subtypes. ^©RSNA, 2018.

KRAS mutation in secondary malignant histiocytosis arising from low grade follicular lymphoma

Background

Transformation of follicular lymphoma most typically occurs as diffuse large B-cell lymphoma, however other forms of transformation such as classic Hodgkin lymphoma and lymphoblastic transformation can occur. Secondary malignant histiocytosis also represents a rare form of transformation, which is thought to occur due to a process of transdifferentiation whereby the lymphoma cells exhibit lineage plasticity and lose all evidence of B-cell phenotype and instead acquire the phenotype of a histiocytic neoplasm. Little is known about the underlying genetic alterations that occur during this unusual process. Comparative genetic analysis of pre- and post-transformation/transdifferentiation would be one tool by which we could better understand how this phenomenon occurs.

Case presentation

Here we report the clinical, immunophenotypic and genetic features of a rare case of secondary malignant histiocytosis, Langerhans cell-type (Langerhans cell sarcoma) arising from a previous low grade follicular lymphoma. FISH analysis confirmed the presence of IgH/BCL2 rearrangement in both the low grade follicular lymphoma (FL) and transformed Langerhans cells sarcoma (LCS) samples, demonstrating a clonal relationship. Comparative whole exome sequencing was then performed, which identified a KRAS p.G13D mutation in the LCS that was not present in the FL.

Conclusions

This report highlights genetic alterations, in particular an acquired somatic KRAS mutation, that may occur during transdifferentiation, with additional significance of KRAS mutation as a possible therapeutic target in cases which otherwise would have limited treatment options.

Electronic supplementary material

The online version of this article (10.1186/s13000-018-0758-0) contains supplementary material, which is available to authorized users.

A Very Rare Case of Right Insular Lobe Langerhans Cell Histiocytosis (CD1a+) Mimicking Glioblastoma Multiforme in a Young Adult

BACKGROUND

Langerhans cell histiocytosis (LCH) is a multisystemic dendritic cell proliferation that is relatively uncommon in adults. Central nervous system LCH outside the pituitary gland is even more uncommon.

CASE DESCRIPTION

We report the case of a 42-year-old man who had complained of right-side hemicranial pain and left arm minor paresis. The symptoms were due to a right insular lobe heterogeneous-enhancing lesion associated with extensive vasogenic edema. The first diagnostic impression suggested glioblastoma multiforme or localized metastasis. The thoracic, abdominal, pelvic computed tomography scan only detected small upper lung inactive nodules suggesting silent focal LCH. A very hard lesion was almost completely removed through a pterional craniotomy approach, with no fluorescence after aminolevulinic acid infusion. The intraoperative biopsy findings ruled out glioma but could not confirm lymphoma. The definitive cerebral biopsy findings showed lymphocytes and histiocytes (CD1a⁺, S-1001⁺), with a diagnosis of intracerebral parenchymal LCH. Fractioned radiotherapy resulted in clinical and radiological remission.

CONCLUSIONS

The present case is so rare it should not be used as a guide. We probably will never see a single intraparenchymal supratentorial central nervous system LCH lesion. However, we hope our report will help colleagues in the future with the thought process.

Senescence and senotherapeutics: a new field in cancer therapy

Cellular senescence is a stress response mechanism ensuring homeostasis. Its temporal activation during embryonic development or normal adult life is linked with beneficial properties. In contrast, persistent (chronic) senescence seems to exert detrimental effects fostering aging and age-related disorders, such as cancer. Due to the lack of a reliable marker able to detect senescence in vivo, its precise impact in age-related diseases is to a large extent still undetermined. A novel reagent termed GL13 (SenTraGor^TM) that we developed, allowing senescence recognition in any type of biological material, emerges as a powerful tool to study the phenomenon of senescence in vivo. Exploiting the advantages of this novel methodological approach, scientists will be able to detect and connect senescence with aggressive behavior in human malignancies, such as tolerance to chemotherapy in classical Hodgkin Lymphoma and Langerhans Cell Histiocytosis. The latter depicts the importance of developing the new and rapidly expanding field of senotherapeutic agents targeting and driving to cell death senescent cells. We discuss in detail the current progress of this exciting area of senotherapeutics and suggest its future perspectives and applications.

Usual and Unusual Manifestations of Familial Hemophagocytic Lymphohistiocytosis and Langerhans Cell Histiocytosis

Familial hemophagocytic lymphohistiocytosis (FHL) and Langerhans cell histiocytosis (LCH) are histiocytic diseases that occur most commonly in young children. Improvements in recognition and treatment have been substantial for both diseases in the past decade, although early and late morbidity continue to be major concerns. These two diagnoses behave differently, although the clinical spectra for both diseases are diverse and can lead to confusion and delays in diagnosis and treatment. This article focuses on the clinical and genetic spectrum of FHL as well as the clinical and treatment variations of LCH.

A Fatal Case of Congenital Langerhans Cell Histiocytosis with Disseminated Cutaneous Lesions in a Premature Neonate

Background. The outcome of neonates with congenital cutaneous Langerhans cell histiocytosis (LCH) is variable. Observations. We report a case of LCH in a female premature neonate born at 33-week gestation. She had disseminated cutaneous lesions, which consisted of hemorrhagic papules and vesicles, with sparse healthy skin areas, and the hands and feet were contracted with scarring and blackened. She was in respiratory failure although no apparent pulmonary or bone lesions on X-rays were noted. Skin biopsy confirmed a diagnosis of LCH due to observation of CD1a⁺ Langerhans cells, which lacked expression of E-cadherin and CD56. The patient died 57 hours after birth. Conclusions. Based on this case and the literature survey, the outcome of premature babies with congenital cutaneous LCH lesions is noted to be unfavorable, with the majority of such cases suffering from multisystem disease.

Insights into the pathogenesis of Langerhans cell histiocytosis: the development of targeted therapies

More than a century after its first description, Langerhans cell histiocytosis (LCH) still remains an intriguing disease. Considerable progress in understanding its biology has been achieved recently. Description of the V600E BRAF mutation in samples of LCH tissue in 2010 was followed by description of additional mutations, all leading to constitutive ERK activation. Current experimental data suggest that LCH is a myeloid neoplasia with inflammatory properties, yet the exact pathophysiology remains poorly understood. Disease management paradigms have changed over time, closely reflecting the evolving view of the nature of the disease. The international Histiocyte Society have conducted three prospective clinical studies on multisystem LCH since the early 1990s. The standard frontline therapy for patients with multisystem LCH based on the cumulative knowledge of those trials consists of 6–12 weeks of initial therapy (daily oral steroids and weekly vinblastine injections), followed by pulses of prednisolone/vinblastine every 3 weeks, for a total treatment duration of 12 months. A currently ongoing study (LCH-IV) with a complex design (five interventional and two observational strata) targets further reduction of mortality and morbidity by tailoring treatment intensity depending on expected risk, as well as by exploring treatment regimens for special locations. Current knowledge on LCH pathobiology opens opportunities for improvement in the patient outcome. The activating BRAF and MAP2K1 mutations collectively accounting for about 75% of the LCH population as well as the resulting constitutive activation of downstream ERK offer an opportunity for targeted treatment. Related issues (eg, finding most effective and less toxic drugs or combinations, appropriate dosage, and optimal treatment duration) must be addressed in controlled prospective trials. Additional mechanisms, such as the interactions of the mutated dendritic cell clone with other inflammatory cells and key cytokines and chemokines, still remain attractive targets for therapeutic intervention, particularly in patients with localized, less aggressive disease.

Bisphosphonates in Langerhans Cell Histiocytosis: An International Retrospective Case Series

Background

Bone is the most common organ of involvement in patients with Langerhans cell histiocytosis (LCH), which is often painful and associated with significant morbidity from pathological fractures. Current first-line treatments include chemotherapy and steroids that are effective but often associated with adverse effects, whereas the disease may reactivate despite an initial response to first-line agents. Bisphosphonates are osteoclast inhibitors that have shown to be helpful in treating bone lesions of LCH. To date, there are no large international studies to describe their role in treating bone lesions of LCH.

Method

We conducted a multicenter retrospective review of 13 patients with histologically proven LCH, who had received bisphosphonates either at diagnosis or at disease reactivation.

Results

Ten patients (77%) had a single system bone disease, and 3 (23%) had bone lesions as part of multisystem disease. Median follow-up time post-bisphosphonate therapy was 4.6 years (range, 0.8 to 8.2 years). Treatment with bisphosphonates was associated with significant pain relief in almost all patients. Twelve (92%) achieved resolution of active bone lesions, and 10 out of them had no active disease for a median of 3.5 years (range, 0.8 to 5 years). One patient did not respond. No major adverse effects were reported in this series.

Conclusion

Bisphosphonates are well-tolerated drugs that can significantly improve bone pain and induce remission in active bone LCH. Future prospective studies evaluating the role of bisphosphonates in LCH are warranted.