Descriptive epidemiology of childhood Langerhans cell histiocytosis in France, 2000-2004

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.

Calvarial Langerhans cell histiocytosis in an Adult: Typical imaging findings in an atypical age group

Langerhans Cell Histiocytosis (LCH) is a rare disorder characterized by neoplastic proliferation of Langerhans-type dendritic cells. LCH is most frequently encountered in the pediatric populations, and involvement of the skeletal system is a common manifestation. Herein, we report a case of LCH presented as an isolated skull lesion in a 66-year-old patient. This presentation has never been reported in the literature at this advanced age and suggests that, despite being exceptionally rare, clinicians should consider LCH in the differential diagnosis of skull lesions in the elderly with classical radiological appearance.

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

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

[Langerhans cell histiocytosis revealed by a temporomandibular joint disorder: Report of a case and review of the craniofacial expressions]

INTRODUCTION

Langerhans cell histiocytosis (HL) is a rare disease that can affect all tissues. Oral manifestations such as mucosal ulcer and tooth mobility are often the first signs of the disease. We report a rare case of mandibular condyle unifocal HL mimicking a temporomandibular joint disorder.

CASE REPORT

A 44-year-old patient presented with a left temporomandibular disorder with painful left preauricular swelling. The imaging assessment found a bone lesion of the left mandibular condyle. A curettage with biopsy was used to diagnose HL. Six months later, the patient had no more pain.

DISCUSSION

The craniofacial clinical expressions of HL mainly concern the bones, which can cause: pain, swelling, fracture, compression of noble organs. The other sites are: oral cavity, skin, lymph nodes, or eyes. Isolated forms are generally benign, and their treatment is discussed between abstention and non-aggressive surgery.

Bone Pathology for Hematopathologists

Bone pathology can be challenging because the skeleton is a living tissue prone to developing a diverse array of inflammatory, metabolic, genetic, reactive, circulatory, and neoplastic abnormalities. Several areas of bone pathology are particularly difficult or problematic for hematopathologists given the close resemblance of some hematologic entities to primary/metastatic bone lesions; examples include plasmacytic disorders versus osteoblastic tumors and lymphoma/leukemia versus round cell tumors of bone. This article provides a conceptual and practical overview of selective bone disorders commonly encountered in the differential diagnosis of hematologic diseases.

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.

Progress towards molecular-based management of childhood Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is characterized by inflammatory lesions containing abundant CD1a+ CD207+ histiocytes that lead to the destruction of affected tissues. This disease has a remarkable pleiotropic clinical presentation and most commonly affects young children. Although the current mortality rate is very low for childhood LCH patients (<2%), reactivation frequently occurs after a long period of disease control and the rates of permanent complications and sequelae remain high. Advances in genomic sequencing technologies in this past decade have highlighted somatic molecular alterations responsible for the disease in around 80% of childhood LCH cases. More than half of these cases harbored the BRAF^V600E mutation, and most other mutations also concerned proteins involved in the MAPKinase pathway. In addition to improving what is known about the LCH pathology, this molecular knowledge provides opportunities to optimize patient management. The BRAF^V600E mutation is associated with more severe presentations of the disease, a high reactivation rate, and a high permanent complication rate; this mutation therefore paves the way for future stratified management approaches. These therapies may be based on the patient's molecular status as well as other clinical characteristics of the disease that are independently associated with undesired events. Moreover, as observed in patients with solid tumors, the BRAF^V600E allele can be detected in the circulating cell-free DNA of patients with severe BRAF^V600E-mutated LCH. Quantification of the plasmatic BRAF^V600E load for this group of patients can precisely monitor response to therapy. Finally, targeted therapies, such as BRAF inhibitors, are new therapeutic options especially designed for refractory multisystemic LCH involving risk organs. However, the long-term efficacy, long-term tolerance, optimal protocol scheme, and appropriate modalities of administration for these innovative therapies for children still need to be defined, a huge challenge.

Diabetes Mellitus, Extreme Insulin Resistance, and Hypothalamic-Pituitary Langerhans Cells Histiocytosis

Background

Langerhans Cell Histiocytosis (LCH) is a rare inflammatory neoplasm characterized by an infiltration of organs by Langerin + (CD207+) and CD1a+ histiocytes. Diabetes insipidus is a frequent manifestation of the disease, while diabetes mellitus is very rare. We report the first case of a 20-year-old man suffering from hypothalamopituitary histiocytosis and diabetes mellitus with serum anti-insulin receptor antibodies.

Case Presentation

A 20-year-old patient was admitted for the evaluation of growth delay and hyperphagia. HbA1c level and fasting blood glucose were in the normal range. The diagnosis of hypothalamopituitary histiocytosis was based on histological features after biopsy of a large suprachiasmatic lesion identified on magnetic resonance imaging (MRI). Association of vinblastine and purinethol was started followed by a second-line therapy by cladribine. During the follow-up, the patient was admitted for recurrence of hyperglycemic states and extreme insulin resistance. The screening for serum anti-insulin receptor antibodies was positive. Each episode of hyperglycemia appeared to be correlated with tumoral activity and increase in serum anti-insulin receptor antibodies and appeared to be improved when the disease was controlled by chemotherapy.

Conclusion

We report the first description of a hypothalamopituitary histiocytosis associated with serum anti-insulin receptor antibodies, extreme insulin resistance, and diabetes. Parallel evolution of glucose levels and serum anti-insulin receptor antibodies seemed to be the consequence of immune suppressive properties of cladribine.

Paediatric and adult-onset male hypogonadism

The hypothalamic-pituitary-gonadal axis is of relevance in many processes related to the development, maturation and ageing of the male. Through this axis, a cascade of coordinated activities is carried out leading to sustained testicular endocrine function, with gonadal testosterone production, as well as exocrine function, with spermatogenesis. Conditions impairing the hypothalamic-pituitary-gonadal axis during paediatric or pubertal life may result in delayed puberty. Late-onset hypogonadism is a clinical condition in the ageing male combining low concentrations of circulating testosterone and specific symptoms associated with impaired hormone production. Testosterone therapy for congenital forms of hypogonadism must be lifelong, whereas testosterone treatment of late-onset hypogonadism remains a matter of debate because of unclear indications for replacement, uncertain efficacy and potential risks. This Primer focuses on a reappraisal of the physiological role of testosterone, with emphasis on the critical interpretation of the hypogonadal conditions throughout the lifespan of the male individual, with the exception of hypogonadal states resulting from congenital disorders of sex development.

Systemic Histiocytosis (Langerhans Cell Histiocytosis, Erdheim-Chester Disease, Destombes-Rosai-Dorfman Disease): from Oncogenic Mutations to Inflammatory Disorders

PURPOSE OF REVIEW

Provide an overview of recent progress in decoding the pathogenesis and treatment of systemic histiocytoses.

RECENT FINDINGS

Advances in molecular techniques over the last few years, enabling the identification of several MAPK mutations in lesion histiocytes, have revolutionized our understanding of histiocytosis that led to a revised classification and new treatments. Since the 2010 discovery of the BRAF^V600E mutation in 57% of Langerhans cell histiocytosis (LCH) lesions, several other kinase mutations have been found, mostly in the MAPK pathway, and also in other key signaling pathways, in LCH, Erdheim-Chester Disease (ECD) and, less frequently, Destombes-Rosai-Dorfman disease (RDD). Those revolutionary breakthroughs enhanced our understanding of the pathogenesis of histiocytosis and led to trials with targeted therapies that demonstrated notable efficacy.

Langerhans' cell histiocytosis of the temporal bone in an adult with central diabetes insipidus

We present a case of Langerhans’ cell histiocytosis in a 40-year-old woman presenting with central diabetes insipidus and right ear pain. As this disease process is often clinically challenging, the presence of certain imaging findings should raise the possibility of this diagnosis. We review the pertinent imaging and correlate with histology and immunohistochemistry leading to the diagnosis.

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

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

Outcome of children with Langerhans cell histiocytosis and single-system involvement: A retrospective study at a single center in Shanghai, China

BACKGROUND

This is a descriptive review of the clinical patterns and outcomes of children with Langerhans cell histiocytosis and single-system involvement (SS-LCH) treated at Shanghai Children's Medical Center.

PROCEDURE

60 evaluable newly diagnosed patients (37 boys, 23 girls) with a median age of 3.9 years (range: 0.3-15.3 years) and histiopathology-confirmed SS-LCH were enrolled from 2010 to 2014. All patients received systemic chemotherapy using either the DAL HX-83 or LCH-II protocol as determined by the physician.

RESULTS

Bone was the most frequently affected organ (56/60, 93.3%). Of the 56 patients suffering from SS-bone disease, 35 (62.5%) had unifocal disease and 21 (37.5%) had multifocal disease. CNS-risk lesions were seen in nine patients (16.1%, 9/56) at diagnosis. Thirty-two patients were treated with the LCH-II protocol and 28 received the DAL HX-83 protocol. No patient received intralesional steroid injection at the time of surgery. CNS-risk lesion correlated with an inferior event-free survival (EFS) for patients with bone disease (62.5 ± 17.1% vs. 90.7 ± 4.5%; p = 0.039). The difference in the 5-year EFS between patients with unifocal and multifocal SS-bone LCH did not reach the statistical significance (93.8 ± 4.3% vs. 75.0 ± 9.7%; p = 0.074). No deaths were observed, leading to a 5-year OS of 100% in the present cohort of patients. Permanent consequences and secondary malignancies were not observed but were also limited by short follow-up.

CONCLUSIONS

Optimal therapy for patients with SS-bone LCH has not been established. Less toxic therapeutic approaches should be considered for these patients and tested in prospective trials.

Merkel cell polyomavirus and Langerhans cell neoplasm

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

The role of parental and perinatal characteristics on Langerhans cell histiocytosis: characterizing increased risk among Hispanics

PURPOSE

Potential roles of inherited and environmental risk factors in pathogenesis of Langerhans cell histiocytosis (LCH), a myeloid neoplastic disorder, are undefined. We therefore evaluated the role of parental and perinatal factors on the risk of this childhood cancer.

METHODS

Information on LCH cases (n = 162) for the period 1995-2011 was obtained from the Texas Cancer Registry. Birth certificate controls were frequency-matched on year of birth at a ratio of 10:1 for the same period. Variables evaluated included parental age, race/ethnicity, size for gestational age, and birth order. Logistic regression was used to generate an adjusted odds ratio (aOR) and 95% confidence interval (CI) testing the association between each factor and LCH.

RESULTS

Few perinatal or parental factors were associated with LCH risk, with the exception of race/ethnicity. Mothers of Hispanic ethnicity were more likely to have children who developed LCH compared to non-Hispanic whites (aOR: 1.51; 95% CI: 1.02-2.25). This risk increased when both parents were Hispanic (aOR: 1.80; 95% CI: 1.13-2.87). Non-Hispanic black mothers were suggested as less likely to give birth to offspring who developed LCH compared to non-Hispanic whites (aOR: 0.50; 95% CI: 0.24-1.02).

CONCLUSIONS

LCH is characterized by somatic mutations in MAPK pathway genes in myeloid precursors. Increased risk for LCH in children of Hispanic parents suggests potential impact of inherited factors on LCH pathogenesis.

Langerhans cell histiocytosis with hemorrhagic uveitis and exudative retinal detachment

Bilateral intraocular involvement in Langerhans cell histiocytosis (LCH) is uncommon. A 15-year-old boy presented with painless decreased vision in right and painful left red eye of 2 weeks duration. Visual acuity was 20/500 and 20/200, respectively. A fixed dilated pupil with exudative retinal detachment was present in the right eye and hemorrhagic iris nodules with hyphema and hypopyon were seen in the left eye. Intraocular pressure was 12 and 31 mmHg, respectively, in each eye. Ocular symptoms were preceded by fever with multiple skin rashes, subcutaneous nodules, and lymph node enlargement. The histopathological examination of skin and lymph node showed histiocytes positive for histiocytic S 100. He was treated with topical steroids and antiglaucoma eye drops along with intravenous vinblastine 6 mg and oral prednisolone (1 mg/kg). Hyphema and hypopyon were resolved, vision improved to 20/320 and 20/80, and intraocular pressure was under control. However, as multisystemic LCH has a poor prognosis, we were unable to save him. Hence, fatal conditions like LCH should also be considered in the differential diagnosis of any hemorrhagic uveitis.

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

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

Atlantoaxial Langerhans cell histiocytosis radiographic characteristics and corresponding prognosis analysis

BACKGROUND

Langerhans cell histiocytosis (LCH) may affect atlas and axis, and there were very few published cases describing a characteristic of LCH of atlantoaxial.

OBJECTIVE

The objective of the study is to investigate the image manifestations of atlantoaxial LCH to improve the in-depth comprehension on it.

MATERIALS AND METHODS

A retrospective study was done of computed tomography (CT) and magnetic resonance imaging in atlas and axis and prognosis was analyzed.

RESULTS

The study included 41 patients (average age 12.9 years and median age 8 years) diagnosed with LCH, with 75.6% under 15 years old. Eighty-four lesions of LCH were identified including 47 in the atlas and 37 in the axis. The osteolytic bone destructions in the atlas and axis were characterized, 22% accompanied by sclerotic margins. Thirteen patients had a compression fracture, 11 in the lateral mass of the atlas and 2 in the C2 vertebral body. Sixteen and three patients had atlantoaxial malalignment and dislocation, respectively. On T2-weighted images, 68.9% showed iso- or low-signal intensity, 27.6% showed hyperintensity signal, and 3.4% showed heterogeneous signal. On postcontrast images, 81.9% showed significant enhancement, 12.5% showed moderate enhancement, and 6.3% showed mild enhancement. CT reexamination of 14 patients indicated atlantoaxial bone destruction relatively repaired in 12 patients. Thirty-three patients were a follow-up, 81.8% had no significant symptoms and 18.2% with remaining symptoms.

CONCLUSIONS

The atlas and axis were affected by LCH, mainly in children. The lateral mass was easily affected and compressed, destruction of the atlas and axis could lead to atlantoaxial joint instability. The prognosis was good in most of the patients.

How I manage pulmonary Langerhans cell histiocytosis

Pulmonary Langerhans cell histiocytosis (PLCH) is a rare sporadic cystic lung disease of unknown aetiology that is characterised by the infiltration and destruction of the wall of distal bronchioles by CD1a⁺ Langerhans-like cells. In adults, PLCH is frequently isolated and affects young smokers of both sexes. Recent multicentre studies have led to the more standardised management of patients in clinical practice. Smoking cessation is essential and is occasionally the only suitable intervention. Serial lung function testing is important because a significant proportion of patients may experience an early decline in forced expiratory volume in 1 s and develop airflow obstruction. Cladribine was reported to dramatically improve progressive PLCH in some patients. Its efficacy and tolerance are currently being evaluated. Patients who complain of unexplained dyspnoea with decreased diffusing capacity of the lung for carbon monoxide should be screened for pulmonary hypertension by Doppler echocardiography, which must be confirmed by right heart catheterisation. Lung transplantation is a therapeutic option for patients with advanced PLCH.The identification of the BRAF^V600E mutation in approximately half of Langerhans cell histiocytosis lesions, including PLCH, and other mutations of the mitogen-activated protein kinase (MAPK) pathway in a subset of lesions has led to targeted treatments (BRAF and MEK (MAPK kinase) inhibitors). These treatments need to be rigorously evaluated because of their potentially severe side-effects.

Late outcomes in children with Langerhans cell histiocytosis

INTRODUCTION

Langerhans cell histiocytosis (LCH) is a rare disease with diverse clinical courses. Despite improvement in survival outcomes in the recent decades, sequelae of the disease remain a concern. This study aimed to provide information on the long-term outcomes in patients with LCH, particularly on the sequelae and any associated factors.

METHOD

Medical records of patients with diagnosis of LCH and being managed in our centre were retrospectively reviewed. Data on the courses of illness, mortality, intervention, types and time of late events were collected and analysed.

RESULTS

70 patients were included with a mean observation time of 12 years (median 10.7 years, range 1-31.3 years). Sequelae related to LCH were present in 56% (n=39), being more common in multisystem diseases and patients with reactivations. Prevalence of sequelae is as follows: orthopaedic related 27%, diabetes insipidus 19%, growth retardation 13%, cosmetic 10%, neurological 7%, hearing 7%, anterior pituitary hormone deficiency 7%, hepatobiliary 4% and ophthalmological 3%. Neurological sequelae could manifest even 10 years after initial diagnosis of LCH. Reactivations, presence of central nervous system (CNS) risk lesions and treatment with radiotherapy were associated with a higher rate of sequelae. The cumulative incidence of reactivation was 34%. Most reactivations occurred in the first 2.5 years after diagnosis.

CONCLUSION

Sequelae were common after LCH, although some were mild. Neurological sequelae could be particularly severe and debilitating. Vigilant long-term follow-up would be essential for optimising patient outcomes. Further studies on the prevention and treatment of CNS disease of LCH are warranted.

Histiocytoses: emerging neoplasia behind inflammation

Histiocytoses are disorders characterised by inflammation and the accumulation of cells derived from the monocyte and macrophage lineages, which results in tissue damage. Although they are often considered rare disorders with protean clinical manifestations, considerable advances in the understanding of their genetics have led to increased clinical recognition of these conditions, and fuelled further insights into their pathogenesis. In this Review, we describe insights into the cells of origin, molecular pathology, clinical features, and treatment strategies for some of the most common histiocytic disorders, including Langerhans cell histiocytosis, Erdheim-Chester disease, and Rosai-Dorfman disease. With the discovery of recurrent mutations affecting the mitogen-activated protein kinase and mTOR-AKT pathways in some of these histiocytoses, our understanding of these diseases has now evolved from the concept of a primary inflammatory condition to that of a clonal neoplastic disease. This understanding has led to the development of effective mechanism-based therapeutic strategies for patients with histiocytic diseases.

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.

[Child Langerhans cell histiocytosis]

DEFINITION

Langerhans cell histiocytosis (LCH) is defined by the association of a clinical and radiological involvement and a biopsy of a pathological tissue. Extension: it can affect any organ or system of the body but most commonly the bone (80% of cases), the skin (33%) and the pituitary (25%). Other organs are concerned such as liver, spleen, hematopoietic system and the lungs (15% each), lymph nodes (5-10%) and central nervous system (CNS) excluding the pituitary (2-4%). Natural history: the natural history of the disease is very heterogeneous, ranging from auto-regressive lesions to a disease affecting multiple organs with fatal consequences, while some lesions may be responsible for permanent sequels. A multidisciplinary approach: the perception of disease from physicians varies greatly depending on their speciality and experience, as well as the presentation of the disease or the short-term treatment outcomes. But whatever the initial view of the treating physician, a multidisciplinary approach to the LCH is recommended as well as the coordination of the necessary care of this systemic disease and its associated morbidity.

THERAPY

current treatment protocols, adapted to the situation of each patient, provide a survival of 98% in children. The sequels, such as diabetes insipidus, hormonal deficits, deafness and even more rarely respiratory failure and sclerosing cholangitis are seen in up to 30% of children.

[Adult Langerhans cell histiocytosis]

Langerhans cell histiocytosis (LCH) is a rare disease affecting both genders and can occur at any age. It often evolves through successive flares, and its severity varies from benign forms that don't require treatment to life threatening disease. Some patients have important functional impairment with psychological and social consequences and prolonged disability. LCH may affect only one organ, with uni- or multifocal involvement or be multisystem disease involving multiple organs. The organs most frequently involved are bones, lung, skin and the endocrinal system. Pulmonary LCH is strongly related to smoking. Some patients have mixed histocytosis combining LCH and other histiocytic disorders. The diagnosis relies on the histological study of tissues samples, and shows tissue infiltration with large cell with pale cytoplasm and reniform nucleus, staining for CD1a and Langerin (CD207) on immunohistochemistry. The BRAF^V600E mutation is observed in tissue samples in approximately half of patients and the activation of the RAS-RAF-MEK-ERK pathway has been shown to be constantly activated in LCH lesions, regardless the BRAF status. These findings represent an important forward step in the understanding of the physiopathology of the disease. Treatment must be adapted to the severity of the disease and goes from conservative observation to systemic chemotherapy. Therapies targeting the RAS-RAF-MEK-ERK pathway are promising treatments for progressive disease.

BRAFV600E and MAP2K1 mutations in Langerhans cell histiocytosis occur predominantly in children

Langerhans cell histiocytosis (LCH) is a proliferative disease of CD1a⁺ /CD207⁺ dendritic cells. Recurrent BRAFV600E and MAP2K1 mutations have been reported in LCH. To investigate the relationship among the mutation, clinical findings, and differentiation status of LCH, respectively, we studied 97 cases of LCH by using Sanger sequencing and immunohistochemistry. The mutually exclusive BRAFV600E and MAP2K1 mutation rates were 32% and 17.5%, respectively. All MAP2K1 mutations were missense mutations without any in-frame deletions; 2 new recurrent missense mutations (ie, p.E38K and p.P105S) were also found. More BRAFV600E and MAP2K1 mutations occurred in children compared with those in adult patients (P = .001), and BRAF mutation was correlated with relapse (P = .009). To the differentiation-related markers, the BRAF/MAP2K1-mut LCH expressed CD14 but rarely expressed CD83 or CD86 (P < .001). On the contrary, BRAF/MAP2K1-wt LCH cells rarely expressed CD14 but expressed CD86, and some also expressed CD83 (P < .001). This indicated that the BRAF/MAP2K1-mut LCH cells had a more immature state than BRAF/MAP2K1-wt LCH cells. Moreover, we also found the BRAFV600E and MAP2K1 mutations were significantly associated with pERK expression (P < .001). Therefore, the RAS/RAF/MEK/ERK pathway might play a more important role in children than in adult patients with LCH.

Genomic Alterations in Langerhans Cell Histiocytosis

The discovery of recurrent somatic genomic alterations in Langerhans cell histiocytosis (LCH) has led to a new understanding of LCH as a clonal neoplastic disorder. Most of the abnormalities described to date affect the RAS/RAF/MEK/extracellular-signal-regulated kinase (ERK) pathway: more than 50% of LCH cases carry activating mutations in BRAF, whereas another 10% to 28% carry activating mutations of MAP2K1, which encodes MEK1. The pathogenetic importance of these mutations has been confirmed by reports of significant clinical responses to RAF inhibitors.

BRAF Mutation Correlates With High-Risk Langerhans Cell Histiocytosis and Increased Resistance to First-Line Therapy

PURPOSE

Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasia with a broad spectrum of clinical manifestations and outcomes in children. The somatic BRAF(V600E) mutation occurs frequently, but clinical significance remains to be determined.

PATIENTS AND METHODS

BRAF(V600E) mutation was investigated in a French LCH cohort. We analyzed associations between mutation status and clinical presentation, extent of disease, reactivation rate, response to therapy, and long-term permanent sequelae.

RESULTS

Among 315 patients with successfully determined BRAF status, 173 (54.6%) carried a BRAF(V600E) mutation. Patients with BRAF(V600E) manifested more severe disease than did those with wild-type BRAF. Patients with BRAF(V600E) comprised 87.8% of patients (43 of 49) with multisystem LCH with risk organ involvement (liver, spleen, hematology), 68.6% of patients (35 of 51) with multisystem LCH without risk organ involvement, 43.9% of patients (86 of 196) with single-system LCH, and 42.1% of patients (8 of 19) with lung-involved LCH (P < .001). BRAF(V600E) mutation was also associated with organ involvement that could lead to permanent, irreversible damage, such as neurologic (75%) and pituitary (72.9%) injuries. Compared with patients with wild-type BRAF, patients with BRAF(V600E) more commonly displayed resistance to combined vinblastine and corticosteroid therapy (21.9% v 3.3%; P = .001), showed a higher reactivation rate (5-year reactivation rate, 42.8% v 28.1%; P = .006), and had more permanent, long-term consequences from disease or treatment (27.9% v 12.6%; P = .001).

CONCLUSION

In children with LCH, BRAF(V600E) mutation was associated with high-risk features, permanent injury, and poor short-term response to chemotherapy. Further population-based studies should be undertaken to confirm our observations and to assess the impact of BRAF inhibitors for this subgroup of patients who may benefit from targeted therapy.

Abdominal manifestations of histiocytic disorders in adults: imaging perspective

Histiocytic disorders (HDs) are a diverse group of diseases characterized by pathologic infiltration of normal tissues by cells of the mononuclear phagocyte system. The spectrum of these diseases ranges from treatable infectious diseases to rapidly progressive, life-threatening conditions. Although they are rare and difficult diagnoses, HDs can be diagnosed with the help of clinical and laboratory analyses, imaging features and tissue biopsy. The clinicopathology and imaging spectrum of select entities belonging to this disorder are presented in this review.

Langerhans cell histiocytosis: therapeutic strategy and outcome in a 30-year nationwide cohort of 1478 patients under 18 years of age

The French national cohort of children with Langerhans cell histiocytosis (LCH) has included 1478 patients since it was established in 1983. LCH therapeutic strategies substantially changed in 1998, so we have divided the cohort into two 15-year periods. Starting in 1998, therapy duration increased from 6 to 12 months, repeated induction therapy was performed in cases showing a poor response to the first induction with vinblastine and steroids, and refractory disease in a risk organ (RO+) was treated with cladribine and cytarabine. A total of 483 (33%) patients were enrolled before 1998, and 995 (67%) after 1998. Five-year survival was 96·6% (95% confidence interval: 95·4-97·5%) overall, improving from 92% pre-1998 to 99% post-1998 (P < 0·001 adjusted to disease extent). This change was supported by an increase in 5-year survival from 60% to 92% in the RO+ group. Survival was particularly associated with cladribine and cytarabine among refractory RO+ patients. Disease reactivation was slightly less frequent after 1998, due to better enrolment of single-system patients, extended therapy duration, and more efficient second-line therapy. The crude rates of endocrine and neurological sequelae (the most frequent sequelae) appeared to improve over time, but this difference was not observed when the analysis was stratified by disease extent.

Langerhans cell histiocytosis: a comprehensive review

Langerhans cell histiocytosis (LCH) is currently regarded as a myeloid neoplasm, with remarkably broad clinical spectrum, ranging from isolated skin or bone lesions to a disseminated disease that can involve nearly any organ. LCH is generally regarded as a sporadic disease that occurs predominantly in the paediatric population. The diagnosis of LCH is confirmed by immunohistochemistry (IHC) by demonstrating the presence of dendritic cell markers such as S100 protein, in addition to CD1a and langerin. Contrary to previous beliefs, recent literature reveals that the pathogenesis of LCH might involve a clonal process implicating BRAF c.1799T>A (p.Val600Glu) and other mutations [(600DLAT) B-RAF and (T599A) B-RAF, somatic MAP2K1 mutations].Through this review article, we have summarised the latest understanding of the biological and salient histological characteristics of LCH and its potential morphological mimics.

Revised classification of histiocytoses and neoplasms of the macrophage-dendritic cell lineages

The histiocytoses are rare disorders characterized by the accumulation of macrophage, dendritic cell, or monocyte-derived cells in various tissues and organs of children and adults. More than 100 different subtypes have been described, with a wide range of clinical manifestations, presentations, and histologies. Since the first classification in 1987, a number of new findings regarding the cellular origins, molecular pathology, and clinical features of histiocytic disorders have been identified. We propose herein a revision of the classification of histiocytoses based on histology, phenotype, molecular alterations, and clinical and imaging characteristics. This revised classification system consists of 5 groups of diseases: (1) Langerhans-related, (2) cutaneous and mucocutaneous, and (3) malignant histiocytoses as well as (4) Rosai-Dorfman disease and (5) hemophagocytic lymphohistiocytosis and macrophage activation syndrome. Herein, we provide guidelines and recommendations for diagnoses of these disorders.

Langerhans Cell Histiocytosis (LCH) in Egyptian Children: Does Reactivation Affect the Outcome?

OBJECTIVE

To report a single centre outcome of management of Langerhans cell histiocytosis (LCH), a clonal disease with involvement of various body systems.

METHODS

Retrospective analysis of 80 pediatric LCH patients at Children Cancer Hospital-Egypt between July 2007 and December 2011 was performed. Patients were stratified and treated according to LCH III protocol. The median follow up period was 42 mo (range: 1.18 to 71 mo).

RESULTS

At wk 6 and 12, 'better' response was obtained in 61 (76 %) and 74 (93 %) patients respectively. Afterwards, reactivation occurred in 25 patients (38 %), of them multiple episodes occurred in 5 patients (6.25 %), managed by repetition of 1st line treatment for once or more. The 5 y overall survival (OS) and event free survival (EFS) was 96.3 and 55 % respectively. At last follow up, better status was reached in 70 patients, 3 in each 'intermediate' and 'worse' status. Three high risk patients died and one patient was lost to follow up.

CONCLUSIONS

In a single Egyptian pediatric LCH experience, the response to treatment is satisfactory and survival remains the rule except in high risk organs disease that still needs a new molecule for salvage. However in multiple reactivations, patients do well with repetition of the 1st line of treatment with or without methotrexate.

The 5-Year EFS of Multisystem LCH With Risk-Organ Involvement Is Suboptimal: A Single-center Experience From India

The study describes an 8-year experience of a single center in managing patients with langerhans cell histiocytosis on the basis of the langerhans cell histiocytosis-III platform. A retrospective case-file review of children diagnosed during 2006 to 2013 was performed. Group 1 (multisystem with risk-organ involvement) patients received an initial treatment of 6 to 12 weeks, followed by continuation treatment to complete 12 months. Drugs included vinblastine, prednisolone, and 6-mercaptopurine. Group 2 (multisystem without risk-organ involvement) patients received a similar treatment, except for 6-mercaptopurine. Group 3 (single-system/multifocal bone disease) patients were treated for a duration of 6 months. Forty-nine patients were treated: 24 (49%), 14 (28.6%), and 11 (22.4%) in groups 1, 2, and 3, respectively. The mean age at diagnosis was 31.6 ± 28.4 months (range, 4 to 120 mo). Five patients abandoned treatment. There were 7 deaths, all in group 1. All patients who died had either a partial response or progressive disease after induction (P=0.000). Among patients with liver involvement, those with sclerosing cholangitis had a greater mortality (P=0.007). A relapse was observed in 12 (24.5%) patients. The frequency of relapse was not different in the 3 groups (P=0.833). The 5-year event-free survival in groups 1, 2, and 3 was 29.3 ± 10%, 58.9 ± 14.6%, and 69.3 ± 15%, respectively (P=0.019). The 5-year overall survival was 100% in groups 2/3 and 68.9 ± 9.8% in group 1 (P=0.011).

Skull Vault Lesions: A Review

OBJECTIVE

The aim of this article is to describe the imaging features of the most common benign or malignant skull vault lesions, which may be focal, multifocal, or diffuse.

CONCLUSION

Imaging features, in association with the age, history, and clinical symptoms of the patient, make it possible to propose a course of action: simple survey, pathologic confirmation, or complete surgical resection.

Hand-Schüler-Christian disease presenting with recurrent, bilateral, symmetrical mandibular lesions in an 8-year-old boy: report of a case

INTRODUCTION

Hand-Schüller-Christian disease (HSC) is the unisystem multifocal form of Langerhans Cell Histiocytosis (LCH) and is primarily seen in infants and children.

CASE REPORT

An 8-year-old boy was referred for acute mandibular pain. His medical history included otic LCH and diabetes insipidus at age of 11 months. Intraorally, a pressure sensitive swelling, and radiographically, extensive bone loss were revealed on the area of lower second primary molars. The primary molars were extracted and histological examination confirmed the final diagnosis of HSC. The patient was treated with chemotherapy and the lesions decreased considerably. Two years later, a new swelling was recorded in the same area bilaterally. Biopsy confirmed recurrent HSC disease and the patient entered an alternative chemotherapy protocol. Six months later, improvement of the lesions was revealed.

CONCLUSIONS

Dentists can contribute to a timely and valid identification of HSC disease by correctly differentially diagnosing lesions of head and neck.