Reactivation and risk of sequelae in Langerhans cell histiocytosis

Clinical outcomes and prognostic risk factors of Langerhans cell histiocytosis in children: Results from the BCH-LCH 2014 protocol study

Langerhans cell histiocytosis (LCH) is a rare myeloid neoplasm mainly affecting young children. This study aimed to evaluate the outcomes of 449 pediatric patients enrolled in the BCH-LCH 2014 study. 52.6% of patients were classified with single-system (SS) LCH, 28.1% with multisystem (MS) risk organ negative (RO-) LCH, and 19.4% with MS RO+ LCH. Three hundred ninety-six patients (88.2%) were initially treated with first-line therapy based on the vindesine-prednisone combination. One hundred thirty-nine patients who lacked a response to initial treatment were shifted to second-line therapy, 72 to intensive treatment Arm S1 (a combination of cytarabine, cladribine, vindesine, and dexamethasone), and 67 to Arm S2 (without cladribine). The 5-year overall survival (OS), progression-free survival (PFS), and relapse rates were 98.2% (median: 97.6 months), 54.6% (median: 58.3 months), and 29.9%, respectively. MS RO+ patients had the worst prognosis among the three clinical subtypes. For the patients initially treated with first-line therapy, the 5-year OS, PFS, and relapse rates were 99.2%, 54.5%, and 29.3%, respectively. Patients in Arm S1 had a significantly better prognosis than patients in Arm S2 (5-year PFS: 69.2% vs. 46.5%, p = .042; relapse rate: 23.4% vs. 44.2%, p = .031). Multivariate analysis revealed that early treatment response, the involvement of RO, skin, and oral mucosa, as well as laboratory parameters, including CRP and γ-GT, were independent risk factors for the PFS of LCH. Thus, the prognosis of LCH in children has been improved significantly with stratified chemotherapy, and progression and relapse remained the challenges, especially for RO+ patients.

Relapses of multisystem/multifocal bone Langerhans cell histiocytosis in paediatric patients: Data analysis from the JLSG-96/02 study

We assessed relapse patterns in paediatric patients with relapsed Langerhans cell histiocytosis (LCH) who were initially treated with the JLSG-96/02 protocol. We analysed 187 relapse events in 101 relapsed LCH patients [31 with multifocal bone (MFB) and 70 with multisystem (MS) at LCH diagnosis] among a total 317 patients enrolled in JLSG-96/-02 studies. Relapse of LCH was defined as an exacerbation of the non-active disease (NAD) condition. Of the 317 patients, 101 (31.9%) had the first relapse at 1.5 years after initiation of therapy. The first relapse and subsequent relapses did not differ between patients with MFB and MS disease. Of the 187 relapse events, relapse occurred as a single-system disease (n = 159; 85%), in which isolated bone relapse (n = 104; 55%) was the most common. Relapse at MS disease with the risk of organ involvement is extremely rare. After relapse(s), most patients underwent chemotherapy (122/187; 65%) and 87% of them achieved NAD status again. The incidence of permanent consequences was significantly higher in patients with relapses than in those without relapses. In the JLSG cohort, bone relapse most occurred in both MFB and MS patients. Most relapses could be effectively controlled by repeated administration of the initial chemotherapy.

Efficacy and safety of vemurafenib in Langerhans cell histiocytosis (LCH): A systematic review and meta-analysis

Almost half of the patients with Langerhans cell histiocytosis (LCH) are refractory to primary induction chemotherapy or undergo reactivation. The ideal treatment modality for refractory/relapsed LCH is yet not evidenced. This review aimed to determine the efficacy and safety of vemurafenib (a BRAF pathway inhibitor) in LCH, particularly the refractory/relapsed cases. The literature search was conducted using PubMed, Embase, CENTRAL, and abstracts published in the SIOP meetings. Studies that described the outcome of patients of LCH being treated with vemurafenib, alone or in combination, were included. A total of 416 studies were screened, and after applying exclusion criteria, 22 studies (n = 107) were included in the final analysis. The first-line therapy was prednisolone plus vinblastine for most patients (n = 92, 86%), and vemurafenib was started upfront in 3 patients (3%). The median time to first clinical response with vemurafenib was one week. The median time to best response was 5.25 months. Out of 107 patients, 62 patients (58%) had ultimately no active disease (NAD) while 39 (36%) had active disease better (ADB), making the overall response rate (ORR) of 101/107, ie, 94.4% (CI 0.88; 0.98). The main adverse effects of vemurafenib were rash or photosensitivity (47%) and other cutaneous adverse events (15%). Vemurafenib is highly efficacious and safe in the treatment of refractory LCH; however, the timing of its commencement and duration of therapy is yet to be established. Larger prospective collaborative trials are needed to answer the appropriate treatment duration and effective maintenance therapy approach.

Central diabetes insipidus developing in a 6-year-old patient 4 years after the remission of unifocal bone Langerhans cell histiocytosis

A six-year-old boy was referred with a one-and-a-half months history of polyuria and polydipsia. At the age of two, he had a single lytic bone lesion in his femoral head, diagnosed as Langerhans cell histiocytosis (LCH) by biopsy at another hospital. As no other affected organs were detected and the affected bone lesion was self-limited, he was not followed up afterward and was doing well. He was diagnosed with diabetes insipidus (DI) by confirming hypernatremia (Na: 148 mEq/l) with hyperosmolar serum (s-Osm 298 mOSM/kg) and inappropriately diluted urine (u-Osm 205 mOSM/kg). His polyuria and polydipsia improved dramatically using the perioral diuretic hormone, and other pituitary functions were not impaired. Magnetic resonance imaging revealed an enlarged pituitary stalk. Sensitive and specific biomarkers of germ cell tumors, including alpha-fetoprotein, placental alkaline phosphatase, and β-hCG in the cerebrospinal fluid, were not detected, indicating relapse of LCH. Genetic analysis revealed a BRAF V600E mutation in the primary bone lesion. We recommend systematic follow-up of patients with a history of LCH, even non-CNS single-system single-site disease, especially with BRAF V600E mutation.

Recurrent Skin Langerhan Cell Histiocytosis Successfully Treated With Indomethacin Monotherapy

Langerhans cell histiocytosis (LCH) often has a recurrent and refractory course despite multiagent treatment modalities. Common relapse treatments include intense or prolonged cytotoxic chemotherapy regimens. There are a few prior reports that the nonsteroidal anti-inflammatory drug indomethacin demonstrated activity against bone LCH. Here we report indomethacin as a successful treatment for a case of chronic skin LCH that failed multiple prior chemotherapy regimens. This experience supports the need for trials to investigate indomethacin as a treatment for LCH both in the relapsed or refractory setting as well as potential combination or maintenance therapy in newly diagnosed patients.

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.

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.

Clinical course of the bony lesion of single-system single-site Langerhans cell histiocytosis - Is appropriate follow-up sufficient treatment?

BACKGROUND

Langerhans cell histiocytosis (LCH) is categorized into three types, which include single-system single-site (SS-s), single-system multiple-site (SS-m) and multisystem (MS). The most commonly affected site in LCH is bone, and the bony lesion of SS-s LCH has a good prognosis. The bony lesion of SS-s LCH has been thought to regress spontaneously. Although treatments such as curettage, direct injection of corticosteroids, and chemotherapy have been performed, regular follow-up is the first line of treatment for the bony lesion of SS-s LCH. For preventing orthopedic sequelae, strict and appropriate follow-up should be performed, but the appropriate period and method of follow-up has not yet been established.

METHODS

In the present study, we retrospectively analyzed a series of 7 cases of patients with SS-s LCH with a bony lesion treated in the Department of Orthopedic Surgery at Kagoshima University Hospital (Kagoshima, Japan) from 2006 to 2015.

RESULTS

The bony lesion regressed spontaneously in all patients. Factors such as location, size, preoperative C-reactive protein (CRP) value, standardized uptake (SUV) value of positron emission tomography (PET), age, sex and direct steroid injection were not related to the clinical course. Temporary expansion of the lesion occurred in 3 patients and a temporary worsening of pain occurred in 1 patient during the follow-up period. These events occurred within 6 weeks after biopsy.

CONCLUSION

Careful follow-up and the use of an appropriate orthosis can lead to a good clinical course for the bony lesion of SS-s LCH. Future research should seek to determine the appropriate follow-up period.

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.

Tertiary lymphoid structures are confined to patients presenting with unifocal Langerhans Cell Histiocytosis

Langerhans cell histiocytosis (LCH) is a neoplastic myeloid disorder with a thus far poorly understood immune component. Tertiary lymphoid structures (TLS) are lymph node-like entities which create an immune-promoting microenvironment at tumor sites. We analyzed the presence and clinical relevance of TLS in n = 104 H&E-stained, therapy-naive LCH lesions of non-lymphoid origin and applied immunohistochemistry to a smaller series. Lymphoid-follicular aggregates were detected in 34/104 (33%) lesions. In line with the lymphocyte recruitment capacity of MECA-79(+) high endothelial venules (HEVs), MECA-79(+)-expressing-LCH lesions (37/77, 48%) contained the most CD3(+) T-lymphocytes (p = 0.003). TLS were identified in 8/15 lesions and contained T-and B-lymphocytes, Follicular Dendritic Cells (FDC), HEVs and the chemokines CXCL13 and CCL21 representing key cellular components and TLS-inducing factors in conventional lymph nodes (LN). Lymphoid-follicular aggregates were most frequently detected in patients presenting with unifocal LCH (24/70, 34%) as compared to patients with poly-ostotic or multi-system LCH (7/30, 23%, p = 0.03). In addition, patients with lymphoid-follicular aggregates-containing lesions had the lowest risk to develop new LCH lesions (p = 0.04). The identification of various stages of TLS formation within LCH lesions may indicate a key role for the immune system in controlling aberrant histiocytes which arise in peripheral tissues.

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 presence of CXCR4+ CD1a+ cells at onset of Langerhans cell histiocytosis is associated with a less favorable outcome

PURPOSE

Langerhans Cell Histiocytosis (LCH) is a neoplastic disorder characterized by tissue accumulating CD1a⁺ histiocytes which frequently carry somatic mutations. Irrespective of mutation status, these LCH-cells display constitutively active kinases belonging to the MAPK pathway. We evaluated, in retrospect, the contribution of individual components of the MAPK-activating and chemotaxis-promoting TNF-CXCR4-CXCL12 axis to LCH manifestation and outcome.

EXPERIMENTAL DESIGN

CXCR4, CXCL12 and TNF protein expression was immunohistochemically analyzed in 70 LCH-affected biopsies. The presence of CXCR4⁺CD1a⁺ cells in peripheral blood (PB) and/or bone marrow (BM) samples was evaluated by flowcytometry in 13 therapy-naive LCH-patients.

RESULTS

CXCL12 was detected in 68/70 (97%) biopsies. CXCR4⁺LCH-cells were present in 50/70 (71%) biopsies; their presence was associated with higher levels of intralesional TNF. Circulating CD1a⁺CXCR4⁺ cells were detected in 4/13 (31%) therapy-naïve LCH-patients which displayed BRAF^V600E (2/4), MAP2K1 (1/4) or no (1/4) mutations in their tissues. These CD11c co-expressing CD1a⁺CXCR4⁺cells migrated to CXCL12 in chemotaxis assays. Lesional CXCR4⁺LCH-cells were detected in 18/20 cases who presented with LCH manifestation at multiple sites and in 5/23 (22%) patients who developed additional lesions after initially presenting with a single lesion. The CXCR4 status at onset proved to be an independent risk factor for LCH reactivation in multivariate analysis (odds ratio 10.4, p = 0.034).

CONCLUSIONS

This study provides the first evidence that CXCR4 is involved in the homing and retention of LCH-cells in CXCL12-expressing tissues and qualifies CXCR4 as a candidate prognostic marker for less favorable disease outcome.

Soft tissue Langerhans cell histiocytosis with secondary bone involvement in extremities: evolution of lesions in two patients

Langerhans cell histiocytosis (LCH) is an uncommon disorder of unknown etiology with a wide spectrum of biological behavior. The most common sites of involvement are bone, skin, and lung. While osseous LCH can result in secondary soft tissue involvement, primary soft tissue LCH in extremities with secondary bone involvement is rare, and little is known about its natural course. We report two adult patients with multi-organ system LCH who had primary soft tissue lesions with secondary involvement of adjoining bones in lower extremities, and illustrate the important role played by various imaging modalities in detection and monitoring of treatment response. We also document spontaneous clinical resolution of LCH lesions without therapy, and positive response of these lesions to chemotherapy.

Multisystem Langerhans cell histiocytosis in children: current treatment and future directions

Langerhans cell histiocytosis (LCH) is a rare (about 3-5 cases per million children aged 0-14 years), non-malignant disease characterized by proliferation and accumulation of clonal dendritic cells, extreme clinical heterogeneity, and an unpredictable course. Three large-scale, international, prospective therapeutic studies (LCH-I to III) for multisystem LCH (MS-LCH) have been conducted by the Histiocyte Society since 1991. The cumulative lessons from these studies are summarized in this review. Patients with MS-LCH represent a heterogeneous group with respect to disease severity and outcome, therefore treatment stratification and risk-tailored treatment are mandatory. The risk for mortality can be predicted based on involvement of 'risk organs' (e.g. hematopoietic system, liver, and/or spleen) at diagnosis and on response to initial therapy (assessed after 6-12 weeks of treatment). Thus, patients without involvement of risk organs (low-risk group) are not at risk for mortality but need systemic therapy in order to control the disease activity and avoid reactivations and permanent consequences. Patients with risk organ involvement (risk group) are at risk for mortality, and lack of therapy response defines a subgroup with a particularly dismal prognosis (high-risk group). Those patients in the risk group who respond to therapy and survive are at risk for reactivations and permanent consequences. The LCH-I study compared the efficacy of vinblastine and etoposide, and concluded that they are equivalent single-agent treatments for children with MS-LCH. However, the results of this trial were inferior with respect to response rate at week 6, disease reactivation rate, and sequelae, when compared with historical trials using more intensive regimens. The combination of prednisolone and vinblastine was established as a standard first-line treatment through the LCH-II and LCH-III studies. The regimen consists of one to two 6-week courses (continuous oral corticosteroids 40 mg/m2/day for 4 weeks, tapered over 2 weeks plus weekly vinblastine intravenous push) of initial therapy, followed by a continuation phase (three weekly pulses of oral prednisolone 40 mg/m2/day for 5 days plus a vinblastine injection). The addition of a third drug to the standard combination (etoposide in LCH-II and methotrexate in LCH-III) failed to significantly improve survival in the risk group. The remaining mortality in the risk group is about 20%, and up to 40% in the high-risk group. Concerning low-risk MS-LCH, comparison of results of the LCH-II study with historical data suggested that the remaining reactivation rate of about 50% (and possibly permanent consequences) could be reduced by prolongation of the total treatment duration. To study this hypothesis, in the low-risk group of the LCH-III study standard maintenance therapy was randomly given for a total treatment duration of 6 and 12 months. Unpublished preliminary data from this recently closed trial suggested that prolongation of the treatment duration may significantly improve reactivation-free survival. In summary, several studies have shown that systemic therapy is indicated for all patients with MS-LCH. A standard two-drug regimen consisting of an initial 'intensive' phase for 6-12 weeks, followed by a less intensive 'maintenance phase' for a total treatment duration of at least 12 months is recommended for patients treated outside of clinical trials. Non-responders, particularly those with progressive disease in risk organs, are eligible for experimental salvage approaches. Remaining questions will be addressed in the upcoming LCH-IV trial, which is in the process of intensive preparation.

Langerhans cell histiocytosis: 37 cases in a single brazilian institution

OBJECTIVES

To improve the level of 'definitive' diagnosis of Langerhans cell histiocytosis by immunohistochemical investigation of the CD1a surface antigen and to compare outcomes in respect to age, gender, stage of the disease, treatment response and level of diagnostic accuracy.

METHODS

A retrospective study was carried out of 37 children and adolescents with possible Langerhans cell histiocytosis between 1988 and 2008. The diagnoses were revisited using immunohistochemical investigations for CD1a, S-100 and CD68 in an attempt to reach definitive diagnoses for all cases.

RESULTS

Before the study, only 13 of 37 patients (35.1%) had a 'definitive' diagnosis; by the end of the study, this number rose to 25 patients (67.6%). All reviewed cases were positive for the CD1a antigen. Overall survival was 88.5%. Multisystem disease (Stage 2; n=19) and absence of response at the 6th week of therapy (n=5) were associated to significantly lower overall survival (p-value = 0.04 and 0.0001, respectively). All deaths occurred in patients with multisystem disease and organ dysfunction at diagnosis. Other potential prognostic factors were not significant. Reactivation episodes occurred in 75% of the patients with multisystem disease. Diabetes insipidus was the most common sequel (21.6%).

CONCLUSION

The level of diagnostic accuracy was increased through immunohistochemistry. The overall survival rate was similar to international multicentric studies. Multisystem disease and absence of response at six weeks of treatment were the most important unfavorable prognostic factors. The frequency of reactivation for patients with multisystem disease was higher than described in the literature, probably because maintenance chemotherapy was used only in two cases.

Langerhans cell histiocytosis in a 5-month-old presenting with biparietal masses

Langerhans cell histiocytosis (LCH) is a rare proliferative disorder that occurs most commonly in the pediatric population as a result of pathological clonal proliferation of Langerhans cells with subsequent damage and destruction to surrounding tissue. Clinically, LCH presents in a variety of ways, which often results in prolonged time to diagnosis and subsequently poorer outcomes. In this case report, the authors describe an unusually early presentation of multisystem LCH in a patient at birth, which resulted in a 5-month delay to diagnosis and treatment. This patient presented both atypically young and with an uncommon initial manifestation of multisystem disease with multiple soft-tissue swellings rather than early skin involvement. Additionally, this patient had an unusual radiographic appearance with biparietal skull destruction on initial skull radiographs and biparietal soft-tissue lesions on CT resembling cephalohematoma at 3 months of age. The clinical and radiological evaluation, pathology, and treatment strategies are discussed, with particular attention paid to the importance of further workup of atypical nonresolving cephalohematomas to prevent disease progression and poorer outcomes.

Small cell tumors of bone

Bone tumors are fortunately rare, but small cell tumors of bone are a relatively common subset of these lesions. They comprise of a diverse group of primary and metastatic neoplasms in both children and adults. The most common small cell tumors of bone include Ewing sarcoma/primitive neuroectodermal tumor, small cell osteosarcoma, multiple myeloma, lymphoma, leukemia, neuroblastoma, rhabdomyosarcoma, and Langerhans cell histiocytosis. Although each entity has its distinctive features, the differential diagnosis of this group of tumors is still challenging because they are all "small, blue, and round cell tumors", histologically. The correct diagnosis of small cell tumors of bone depends on an evaluation of clinical, radiologic, pathologic, and genetic features. Patients' age and sex are very important, as are the signs and symptoms at presentation. Radiologically, which bone is involved, the specific portion of the bone (epiphysis, metaphysis, or diaphysis; cortex vs. medulla) involved, and the radiographic manifestations (lytic, blastic, or mixed lytic and blastic) are also often critical parameters for the diagnosis. In recent years, with a better understanding of the molecular and cytogenetic background of several small cell tumors, more accurate diagnoses have been supported by the clinicopathologic criteria and by a panel of immunohistochemical studies. In this review we will provide an overview of the clinical, radiologic, pathologic, and genetic characteristics of these tumors.

Nationwide survey of single-system single site Langerhans cell histiocytosis in Japan

BACKGROUND

Since neither a standard treatment nor a protocol study for single-system single site (SS-s)-type Langerhans cell histiocytosis (LCH) exists, we conducted a nationwide survey in Japan to clarify the epidemiology and clinical outcome of this subtype.

PROCEDURE

Questionnaires regarding the clinical course of children with SS-s-type LCH diagnosed between 1995 and 2006 were sent to all members of the Japanese Society of Pediatric Hematology.

RESULTS

One hundred forty-six children with histologically proven SS-s LCH were evaluable. The most frequently affected organ was bone (82%), followed by skin (12%). Few patients (14%) had a CNS-RISK lesion defined by the Histiocyte Society. Patients with a skin lesion were diagnosed at a significantly younger age than patients with a bone lesion (median: 6 months vs. 5 years 11 months, P < 0.001). The treatment regimen varied, but one-third of the patients in total and 71% of patients with a CNS-RISK lesion received chemotherapy that did not include etoposide. All but one patient attained remission. Ten patients (7%) showed reactivation. Of these, all eight with an initial bone lesion only exhibited reactivation in the bone(s). One patient with an initial skin lesion exhibited reactivation in the thymus. None of the patients died from disease progression or treatment complications.

CONCLUSIONS

Our retrospective study, in which a relatively large proportion of the patients received chemotherapy, reveals that patients with SS-s LCH have a good prognosis. A prospective study should be conducted to confirm this and to identify the most effective and least toxic therapy for SS-s LCH.

Prognostic indicators for sensorineural hearing loss in temporal bone histiocytosis

OBJECTIVE

Our review aims: (1) to highlight the suspicion of sensorineural hearing loss (SNHL) in temporal bone Langerhans' cell histiocytosis (LCH); (2) to assess the evolution of SNHL in this pathology; (3) to identify radiologic findings of the otic capsule invasion by LCH; (4) to determine prognostic factors for SNHL in temporal bone LCH.

METHODS

We performed a literature review through MEDLINE for SNHL in temporal bone LCH related articles that were published between 1954 and 2008. We identified 12 related studies of which 18 patients were noted. We also added our case to this series. The information from the reports was analyzed to characterize the clinical and demographic data and to focus on the sensorineural hearing aspect of the disease and on the damage of the semicircular canals (SCC) and the cochlea.

RESULTS

Ten percent of patients with temporal bone LCH presented SNHL. The mean age of patients is 3.5 years among children and 35.5 years among adults. Male to female ratio is 1:1.14. There were 13 unilateral cases, 6 bilateral cases and 1 case of multisystemic histiocytosis. Cochlea and SSCs were involved in 4 and 20 temporal bones, respectively. The lateral SCC is the most frequently eroded canal. In 23 ears hearing level was reported: 15 ears had a SNHL and the remaining was a mixed or a conductive hearing loss type. 10 ears suffered from a profound hearing loss and none of them improved after treatment regardless otic capsule affected structures. In all cases of normal hearing, moderate hearing loss and severe hearing loss before treatment cochlea have not been affected. However a single or two semicircular canals invasions have been noted. Where it is reported (15 out of 25 temporal bone) there was a radiological healing of the otic capsule lesion after treatment. Remineralization occurs 6 months after treatment.

CONCLUSION

In LCH, hearing loss level before treatment can be considered as a prognostic indicator for hearing in response to treatment. Even though bone mineralization is essential for a hearing improvement, radiological healing is not a prognostic factor for better hearing level after treatment.

Reactivations in multisystem Langerhans cell histiocytosis: data of the international LCH registry

OBJECTIVE

To assess multisystem Langerhans cell histiocytosis reactivation and its impact on morbidity and mortality.

STUDY DESIGN

Retrospective analysis of 335 patients with MS-LCH and documented complete disease resolution (NAD1).

RESULTS

The probability of a reactivation within 5 years of NAD1 was 46%. The first reactivation occurred within 2 years after NAD1 in most of the patients. Of 134 events, 35% were confined to skeleton, 24% were single-system nonbony lesions, 24% were multisystem reactivations without risk-organ involvement, and 10% with risk-organ involvement. In 7%, the location was unspecified. Only 3 deaths (2.2%) were documented within the context of a first reactivation. Second disease resolution (NAD2) was achieved in 85% of the cases. The probability of a second reactivation within 5 years of NAD2 was 44%. The risk for permanent consequences in patients with reactivations was higher, compared with patients without reactivation (RHR 2.2, P = .046).

CONCLUSIONS

Reactivation is a frequent and early event in MS-LCH, but involvement of risk organs at reactivation is rare and mortality is minimal. However, reactivations increase the risk for permanent consequences by about 2-fold. Prospective trials targeting reduction of acute morbidity and permanent disabilities through nontoxic treatment of the reactivations are warranted.

Langerhans' cell histiocytosis of the temporal bone in children

OBJECTIVE

Langerhans' cell histiocytosis (LCH) is a rare pathology that implies an abnormal proliferation of these kinds of cells associated with a granular infiltration that affects different structures of the human body, including the temporal bone. The authors present their series of LCH of the temporal bone in children at the Sainte-Justine university hospital. The twofold objective of this study is to illustrate the clinical presentation, management and prognosis of this disease, and to compare these results with previously reported series.

METHODS

A retrospective study was conducted between 1984 and 2007 with patients diagnosed and treated for a LCH of the temporal bone at the Sainte-Justine university hospital, a paediatric tertiary care center. A chart review was performed to obtain demographic, clinical, paraclinical, and therapeutic data. They were analysed and compared to other published series. Through a MEDLINE query, we found that since 1966, 50 articles dealing with a LCH of the temporal bone have been published.

RESULTS

Fifty-nine cases of LCH were diagnosed and among them, 10 children had temporal bone involvement. They were four females and six males with a mean age of 3.28 years. The two most frequent clinical manifestations were the presence of a mass in the temporal region (70%) and otitis (60%). Two of our patients had a unifocal lesion of the temporal bone implicated. Eight patients had a multisystem involvement among which, two showed evidence of organ dysfunction. In 80% of cases, the diagnosis was made by immunohistochemical findings of the S-100 protein and/or the CD1 antigen. The common radiological finding on a skull CT scan is a lytic lesion in the temporal bone. Seven patients were treated by chemotherapy, two were treated by radiotherapy as a primary treatment, and one received radiotherapy for a recurrence on the pituitary gland. Finally, one patient was treated with local steroid injections. Two patients had a recurrence. All our patients were in total remission on a mean average of 1.6 years after the diagnosis. Our results concord with other studies in which the prognosis of unifocal bone disease is excellent and children with a multifocal disease have a survival rate of 65-100%.

CONCLUSION

LCH is a rare disease. A high-index suspicion should be raised in the context of a temporal mass, chronic otitis, and otorrhea. A biopsy is recommended in the presence of a temporal bone lytic lesion. Chemotherapy is the preferred therapeutic modality.

Langerhans cell histiocytosis: update for the pediatrician

PURPOSE OF REVIEW

Langerhans cell histiocytosis is the commonest of the histiocytic disorders. Owing to the relative rarity of the condition, it remains a disease in which the diagnosis is often delayed or missed and in which many questions remain unanswered, ranging from etiology and pathogenesis to therapy. The management is often frustrating for care-givers and parents/patients. The purpose of the review is therefore to raise awareness of the disease and to highlight the clinical findings that should make the pediatrician or primary care-giver suspect the diagnosis, as well as current thinking regarding management of the various and diverse manifestations of this disease.

RECENT FINDINGS

We discuss new and interesting insights into the biology of Langerhans cell histiocytosis that raise the possibility of future targeted therapy. Important points in the diagnosis, investigation and management of the various forms of the disease are also discussed.

SUMMARY

We present a review of childhood Langerhans cell histiocytosis, highlighting new insights into pathogenesis and management of the various forms of this complex disease.