Hematopoietic stem cell transplantation in patients with severe Langerhans cell histiocytosis and hematological dysfunction: experience of the French Langerhans Cell Study Group

Vemurafenib combined with chemotherapy achieved sustained remission in pediatric LCH: a multi-center observational study

BACKGROUND

Langerhans cell histiocytosis (LCH) is a myeloid neoplasia with potentially fatal consequences, and about 2/3 of cases involve the BRAFV600E kinase-activated mutation. Vemurafenib, a BRAF inhibitor, has demonstrated significant clinical improvements in LCH. However, the high relapse rate of LCH following cessation of vemurafenib therapy remains a major challenge, and alternative treatment strategies require further investigation.

METHODS

In this retrospective multi-center study, we evaluated the efficacy and safety of vemurafenib combined with conventional chemotherapy in patients with severe or refractory LCH.

RESULTS

Seventeen patients were enrolled in the study, with eleven classified as risk organ involvement (RO +). Six received the combination therapy as the primary treatment, and eleven after being refractory to prior chemotherapy. The overall response rate was 94.1%. Progression-free survival among all 17 patients was 70.6% (12/17) at a median follow-up of 32 months, and relapse-free survival among the 15 patients with discontinuation after a response was 73.3%(11/15) at a median follow-up of 34 months. Five of six patients (83.3%) with myeloid BRAFV600E mutations demonstrated molecular remission. The overall survival rate was 100%. Adverse events were mostly classified as grades 1 or 2.

CONCLUSION

Our data suggest that the combination of vemurafenib and chemotherapy can achieve sustained clinical and molecular level relief in children with LCH, and side effects are tolerable.

The influence of clinical features mimicking primary immunodeficiency diseases (mPID) on children with Langerhans cell histiocytosis (LCH) - Four with mPID among 39 LCH children from one referral center during 18-year period

BACKGROUND

Recurrent or refractory infections can be a warning sign of primary immunodeficiency diseases (PID). Such mimicking PID (mPID) can occur in patients with Langerhans cell histiocytosis (LCH). Because some cases with refractory molluscum contagiosum-like lesions and persistent otorrhea are finally diagnosed with LCH, we wondered whether such mPID can occur in LCH children and affect on their prognosis.

METHODS

We retrospectively reviewed all children with LCH at our institute from 2001 to 2018. A complete medical review of sex, age, symptoms, treatment course, and outcome comparison was performed.

RESULTS

Of 39 enrolled LCH patients, three had persistent otorrhea and one had refractory molluscum contagiosum-like lesions despite aggressive antibiotic therapy. These four cases with mPID had significantly higher rates of multi-system involvement, recurrence and 5-month more lag time, but no risk organ (liver, spleen and bone marrow) involvement compared to those without mPID, although bone and skin were the most involved in both groups. Overall, the lag-time in multi-system was longer than that in single-system involvement (median 2.5 vs. 1.0 months; p = 0.003). The diagnosis-age of risk organ involvement was younger than those without (median 8 vs. 43 months; p = 0.004). There were no significant differences in diagnosis-age, single/multi-system and risk organ involvement between remission and recurrence groups. All were alive excluding four who were lost to follow-up.

CONCLUSIONS

The LCH children with mPID had greater lag time, multi-system involvement, recurrence and more refractory treatment including transplantation despite the ratio of bone and skin lesions equal to those without mPID.

Langerhans Cell Histiocytosis of the Gastrointestinal Tract: Evidence for Risk Organ Status

OBJECTIVE

To investigate the "risk status" of Langerhans cell histiocytosis (LCH) of the gastrointestinal tract.

STUDY DESIGN

Outcomes from 43 published cases of patients with LCH and gastrointestinal tract involvement were matched to 43 patients with LCH without gastrointestinal tract involvement cared for at our institution. Comparisons were made of the 5-year overall survival rates determined from Kaplan-Meier survival curves for the entire cohort of patients, as well as subgroups defined by lack of risk organ involvement and later era of treatment (to control for temporal changes in LCH treatment regimens). In addition, an association between LCH-gastrointestinal tract and risk organ involvement was investigated.

RESULTS

The 5-year overall survival for children with LCH-gastrointestinal tract (45.3%) was significantly worse than for those without gastrointestinal tract involvement (94.6%; P = .001). This difference remained significant after we excluded risk organ involvement (53.6%% vs 100%; P = .001), and analyzing subjects diagnosed after 2000 (75% vs 100%; P = .012). A 4-fold increase in risk organ involvement with LCH-gastrointestinal tract was observed (OR 4.359; 95% CI 1.75-10.82, P = .001).

CONCLUSIONS

This limited retrospective study suggests that patients with LCH-gastrointestinal tract involvement may have decreased survival, independent of risk organ involvement, and provides evidence to support a prospective study to evaluate risk organ status of LCH-gastrointestinal tract. LCH-gastrointestinal tract may be associated with a 4-fold risk for risk organ involvement. Attention to gastrointestinal symptoms and LCH-gastrointestinal tract in young children diagnosed with LCH is warranted.

Autologous hematopoietic stem cell transplantation for efficient treatment of multisystem, high-risk, BRAF V600E-negative Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a disorder caused by clonal proliferation of CD1a⁺/CD207⁺ cells and characterized by varying degrees of organ involvement. Treatment of LCH is risk adapted; patients with multisystem disease and risk-organ involvement require more intensive therapy. Optimal therapies for multisystem, high-risk LCH remain uncertain. Recently, targeted therapy using inhibitors of mutated BRAF (the gene encoding serine/threonine-protein kinase B-Raf) has proven very effective in patients with multisystem refractory LCH. Herein, we report a case of LCH with involvement of the bones, liver, and lymph nodes. Using next-generation sequencing of the patient’s pathological sample, we identified a mutation in MAP2K1 in exon 3 (c.362G>C, p.Cys121Ser) and no mutation in BRAF; thus, high-risk, multisystem LCH with MAP2K1 mutation and wild-type BRAF was diagnosed. After four chemotherapy treatments (COEP regimen), the patient received autologous hematopoietic stem cell transplantation (auto-HSCT). Complete remission was confirmed by follow-up positron emission tomography–computed tomography, which showed no lesions in liver, lymph nodes, or bones compared with the pretreatment period. To date, the patient has sustained good health for 24 months. In conclusion, auto-HSCT may be an effective treatment option for high-risk, multisystem BRAF V600E-negative LCH.

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.

Treatment of Multifocal Multisystem BRAF Positive Langerhans Cell Histiocytosis with Cladribine, Surgery and Allogenic Stem Cell Transplantation

Langerhans cell histiocytosis (LCH) is a very rare disease in adults and as well a very rare cause of sellar expansion. The clinical presentation can be heterogeneous, from a single bone lesion to potentially fatal, widespread disease. We describe the difficulties with the diagnosis and treatment of LCH as well as successful treatment with cladribine chemotherapy and allogeneic stem cell transplantation.

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.

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.

Cladribine and cytarabine in refractory multisystem Langerhans cell histiocytosis: results of an international phase 2 study

An international phase 2 study combining cladribine and cytarabine (Ara-C) was initiated for patients with refractory, risk-organ-positive Langerhans cell histiocytosis (LCH) in 2005. The protocol, comprising at least two 5-day courses of Ara-C (1 g/m(2) per day) plus cladribine (9 mg/m(2) per day) followed by maintenance therapy, was administered to 27 patients (median age at diagnosis, 0.7 years; median follow-up, 5.3 years). At inclusion, all patients were refractory after at least 1 course of vinblastine (VBL) plus corticosteroid, all had liver and spleen involvement, and 25 patients had hematologic cytopenia. After 2 courses, disease status was nonactive (n = 2), better (n = 23), or stable (n = 2), with an overall response rate of 92%. Median disease activity scores decreased from 12 at the start of therapy to 3 after 2 courses (P < .0001). During maintenance therapy, 4 patients experienced reactivation in risk organs. There were 4 deaths; 2 were related to therapy toxicity and 2 were related to reactivation. All patients experienced severe toxicity, with World Health Organization grade 4 hematologic toxicity and 6 documented severe infections. The overall 5-year survival rate was 85% (95% confidence interval, 65.2%-94.2%). Thus, the combination of cladribine/Ara-C is effective therapy for refractory multisystem LCH but is associated with high toxicity.

Haploidentical parental hematopoietic stem cell transplantation in pediatric refractory Langerhans cell histiocytosis

Children with MS-LCH that fail to respond to conventional chemotherapy have poor outcomes. HSCT represents a potential salvage approach. It has been applied in over 50 cases in recent years. HSCT can achieve greater disease control than chemotherapy, but it carries a high risk of transplant-related mortality; thus, the haploidentical parental HSCT is used infrequently in pediatric refractory LCH. We report the first successful haploidentical parental HSCT, with no T-cell depletion, in two girls, aged 26 months and five months, with refractory MS-LCH. The mothers were donors with 5/6 and 4/6 HLA matches, respectively. The conditioning regimen included busulfan + cyclophosphamide + etoposide + antithymocyte-globulin ± fludarabine; the GVHD prophylaxis was based on cyclosporine + methotrexate ± mycophenolate-mofetil ± zenapax. In both cases, the stem cells were sourced from peripheral blood and BM, which included CD34+ cells (13.17 × 10(6)/kg and 40.23 × 10(6)/kg, respectively). These patients survived and showed no signs of disease activity in 54- and 44-month post-HSCT follow-ups. Our results indicated that, for patients that fail chemotherapy delivered early in the disease, but do not show organ dysfunction progression, it may be possible to achieve successful haploidentical parental HSCT with a strong myeloablative regimen.

Pathological consequence of misguided dendritic cell differentiation in histiocytic diseases

Histiocytic disorders represent a group of complex pathologies characterized by the accumulation of histiocytes, an old term for tissue-resident macrophages and dendritic cells. Langerhans cell histiocytosis is the most frequent of histiocytosis in humans and has been thought to arise from the abnormal accumulation of epidermal dendritic cells called Langerhans cells. In this chapter, we discuss the origin and differentiation of Langerhans cells and dendritic cells and present accumulated evidence that suggests that Langerhans cell histiocytosis does not result from abnormal Langerhans cell homeostasis but rather is a consequence of misguided differentiation programs of myeloid dendritic cell precursors. We propose reclassification of Langerhans cell histiocytosis, juvenile xanthogranuloma, and Erdheim-Chester disease as inflammatory myeloid neoplasias.

Langerhans cell histiocytosis with digestive tract involvement

Gastrointestinal tract (GIT) involvement in Langerhans cell histiocytosis (LCH) is not commonly described. We present two children presenting with GIT involvement with LCH, one successfully treated on standard protocol and other being treated on a protocol for relapsed disease. A review of literature showed almost 95% children were less than 2 years of age and 62% were females. Vomiting, abdominal pain, constipation, intractable diarrhea, malabsorption, bloody stools, protein-losing enteropathy, and even intestinal perforation are some of the reported symptoms. More than 50% patients died within 18 months from diagnosis.

Successful treatment of refractory Langerhans cell histiocytosis with pulmonary aspergillosis by reduced-intensity conditioning cord blood transplantation

The prognosis of multisystem LCH in children with risk organ involvement is extremely poor when they fail to respond to conventional chemotherapy. In such patients, allogeneic SCT may produce complete and sustained remission; however, high-dose myeloablative regimens are frequently associated with treatment-related morbidity and mortality. More recently, allogeneic SCT following an RIC regimen has been performed as an alternative salvage approach. We describe a nine-month-old boy with refractory multisystem LCH with pulmonary aspergillosis who was successfully treated with reduced-intensity cord blood transplantation.

Hematopoietic stem cell transplantation in Langerhans cell histiocytosis: case report and review of the literature

The prognosis in children with LCH who do not respond to the conventional therapies is very poor. SCT may be a new approach. However, there are limited data about the results of the transplantations. Herein we report a patient with refractory multisystem LCH who underwent allogeneic bone marrow transplantation and is disease and treatment free 54 months after transplantation. Further studies are required to establish the role of SCT in refractory LCH.

The use of reduced-intensity stem cell transplantation in haemophagocytic lymphohistiocytosis and Langerhans cell histiocytosis

Allogeneic stem cell transplant is curative for haemophagocytic lymphohistiocytosis (HLH) and refractory Langerhans cell histiocytosis (LCH). However, patients frequently have significant pre-transplant morbidity and there is high TRM. Because HLH is caused by immune dysregulation, we surmised that a reduced-intensity conditioned (RIC) regimen might be sufficient for cure, while decreasing the TRM. In 2006, we reported the outcome of 12 patients treated with RIC SCT from a matched family/unrelated or haploidentical donor. Here we discuss the update of these patients, including a total of 25 patients treated with RIC SCT for HLH and three for LCH. Twenty-one of the twenty-five patients with HLH (84%) are alive and well with remission at a median of 36 months from SCT. Mortality included pneumonitis (n=3) and hepatic rupture (n=1). All three patients treated with RIC SCT for LCH remain alive and in remission at a median of 5.1 years from SCT. Seven of twenty-four survivors (one with LCH) have mixed chimerism but remain disease-free. These data are supported by other groups including 100% survival in seven patients with HLH and 78% survival of nine patients with LCH. In summary, RIC compares favourably with conventional SCT with long-term disease control in surviving patients with both HLH and LCL, despite a significant incidence of mixed chimerism.

Successful outcome of Langerhans cell histiocytosis complicated by therapy-related myelodysplasia and acute myeloid leukemia: a case report

BACKGROUND

Various therapeutic options are available for the management of Langerhans cell histiocytosis. However, treatment administered to control this disease may be complicated by acute leukemia.

CASE PRESENTATION

A 34 years old male was diagnosed to have Langerhans cell histiocytosis in March 1999. Unfortunately, the cytotoxic chemotherapy and radiotherapy given to control the repeated relapses and exacerbations of the primary disease predisposed him to therapy-induced myelodysplastic syndrome which transformed into acute myeloid leukemia. After achieving complete remission of his leukemia, the patient received an allogeneic hematopoietic stem cell transplant. The allograft was complicated by chronic graft versus host disease that was controlled by various immunosuppressive agents and extracorporal photophoresis.

CONCLUSION

Management of complicated cases of histiocytosis requires various therapeutic modalities and a multidisciplinary approach. Having complications of therapy eg myelodysplasia or acute leukemia make the outcome more dismal and the management options limited to aggressive forms of treatment. High dose chemotherapy followed by an allograft may be a curative option not only for therapy-related myelodysplasia/acute leukemia, but also for frequently relapsing and poorly controlled Langerhans cell histiocytosis.

Successful treatment of refractory Langerhans cell histiocytosis by allogeneic peripheral blood stem cell transplantation

We describe a six-yr-old boy who exhibited typical signs and symptoms of LCH with EBV-associated hemophagocytic syndrome from the age of 15 months. Multiple courses of conventional chemotherapy achieved only marginal improvement over the ensuring five yr. During this period, this boy experienced recurrent episodes of hemophagocytic syndrome associated with CMV infection. Five yr after the first diagnosis of LCH, the patient was treated with allogeneic PBSCT from his HLA-identical eight-yr-old brother. PBSCT was performed using a TBI-incorporating conditioning regimen comprising TBI, busulfan, and cyclophosphamide. Diabetes insipidus, typically a permanent consequence of LCH, was well controlled by DDAVP therapy. At the time of writing, this boy is alive and well, and had been disease-free for more than two yr after the PBSCT.

Systemic and endocrine manifestations of Langerhans' cell histiocytosis: current concepts in diagnosis and management

Langerhans' cell histiocytosis (LCH) is a rare disease of unknown etiology and variable biologic behavior and course. Almost every organ can be affected; however, it frequently involves the bones, lungs, skin and lymph nodes. LCH exhibits a particular predilection for involvement of the hypothalamo-pituitary axis resulting in diabetes insipidus and/or other anterior pituitary deficiencies. Although LCH can sometimes resolve spontaneously, it usually follows a chronic course and systemic treatment is mandatory for the management of multisystem disease. However, a significant number of patients will develop at least one permanent sequela as a consequence of the disease, with diabetes insipidus being the most common. A multidisciplinary approach is always needed in diagnosis, treatment and follow-up of all patients with LCH.

Drug therapy for the treatment of Langerhans cell histiocytosis

Langerhans cell histiocytosis results from the abnormal accumulation of a class of dendritic cells normally found in the skin, which proliferate in many organ systems along with lymphocytes, macrophages and eosinophils. Standard therapy for Langerhans cell histiocytosis includes vinblastine and prednisone with or without methotrexate and mercaptopurine, depending on the extent of disease. Effective therapies for patients unresponsive to the above include cytosine arabinoside and cladribine. Thalidomide has proven useful for patients with Langerhans cell histiocytosis of the skin and/or bone. Emerging therapies include the use of monoclonal antibodies against the CD1a or CD52 epitopes found on Langerhans cells. Specific therapies directed against the cytokines that are apparently critical to the abnormal proliferation have not yet been defined.

Adult Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a proliferative histiocytic disorder of unknown cause originating from dendritic cells. The clinical presentation of LCH is highly variable. Although the features of this disease have been well described in children, they remain poorly defined in adults. Here, we review the current knowledge about adult LCH, focussing on clinical presentation, diagnosis, treatment, and prognosis.

Improved outcome of treatment-resistant high-risk Langerhans cell histiocytosis after allogeneic stem cell transplantation with reduced-intensity conditioning

Children with multisystem Langerhans cell histiocytosis (LCH) and risk organ involvement who fail to respond to conventional chemotherapy have an extremely poor prognosis. Myeloablative stem cell transplantation (SCT) as a possible salvage approach for these patients has been associated with a high risk of transplant-related mortality. Therefore, allogeneic stem cell transplantation following a reduced-intensity conditioning regimen (RIC-SCT) has recently been performed as an alternative salvage approach. We report on the experience with allogeneic RIC-SCT in nine pediatric high-risk LCH patients. Conditioning regimen included fludarabine in all patients, melphalan in eight patients, total lymphoid irradiation in six patients, total body irradiation in two, antithymocyte globulin in five, and Campath in four patients. RIC-SCT was well tolerated with regard to common procedure-related complications. Two patients died 50 and 69 days after RIC-SCT, respectively. Seven out of the nine patients survived and showed no signs of disease activity (including one with nonengraftment and full autologous hematopoietic recovery) after median follow-up of 390 days post-SCT. Based on this observation, we conclude that RIC-SCT is a feasible procedure with low transplant-related morbidity and mortality and a promising new salvage approach for high-risk LCH patients with resistant risk organ involvement.

Predictors of outcome in children with Langerhans cell histiocytosis

BACKGROUND

Our goal was to examine the clinical course of patients with Langerhans cell histiocytosis (LCH), with a special emphasis on bone disease and to attempt to identify and examine the factors that may predict reactivation and overall prognosis.

PROCEDURE

We conducted a retrospective chart review of 132 consecutive pediatric patients treated at Children's Hospital Los Angeles for LCH from 1984 to 2001.

RESULTS

The risk for reactivation after initial management is significantly higher for patients with multiple bone and those with multiple organ involvement as compared with patients who had a single bone lesion (hazard ratios are 7.1 and 11.6). Patients younger than 1 year in the multiple organ group have an increased risk of death at 2 years when compared with the older patients in that group (hazard ration = 6.2, P = 0.022). Endocrine abnormalities were seen in 20% and 7.5% of patients with or without skull lesions respectively.

CONCLUSIONS

Patients with LCH involving only the bones have a significantly better outcome than those with other organ involvement. Patients with multiple organ involvement who are less than 1 year of age are at high risk of death and should be approached more aggressively upfront.

Multi-centre pilot study of 2-chlorodeoxyadenosine and cytosine arabinoside combined chemotherapy in refractory Langerhans cell histiocytosis with haematological dysfunction

The aim of this study was to assess the efficacy and adverse effects of 2-chlorodeoxyadenosine (2-CdA) and cytosine arabinoside (Ara-C) in children with refractory Langerhans cell histiocytosis (LCH) and haematopoietic dysfunction. Ten patients, with a median age at diagnosis of 0.5 years, were enrolled in this study. Treatment comprised at least two courses of Ara-C (1000 mg/m(2)/d) and 2-CdA (9 mg/m(2)/d) administered for 5d every 4 weeks; subsequent median follow-up was 2.8 years (range 0.03-6.4 years). Among the 7 patients who received at least two courses of therapy, disease activity decreased in 6 patients, and control of disease was achieved in all patients after a median delay of 5.5 months. All patients suffered World Health Organisation (WHO) grade 4 haematological toxicity. Two septic deaths occurred shortly after administration of the first course of 2-CdA/Ara-C; a third patient was withdrawn from the trial after the first course and subsequently died following haematopoietic stem cell transplantation. This series is small, but we conclude that 2-CdA and Ara-C combined chemotherapy probably has major activity in childhood refractory Langerhans cell histiocytosis.

A new clinical score for disease activity in Langerhans cell histiocytosis

OBJECTIVE

To develop an objective tool for assessing disease activity in patients with Langerhans cell histiocytosis (LCH).

METHOD

Scoring system was developed and applied to a database containing information on 612 patients.

RESULTS

At diagnosis, the score distribution was highly asymmetrical: the score was between 0 and 2 in 74% of cases, 3-6 in 16%, 7-10 in 3%, and more than 10 in 6%. The 5-year mortality rates were 1, 4.4, and 43.4%, respectively, among patients with initial scores of 0-2, 3-6, and >6. Stability or an increase of the score at 6 weeks was highly predictive of death among patients with initial scores above 6, while score stability had no significant impact on vital outcome among patients with low or moderate scores at diagnosis.

CONCLUSIONS

This LCH disease activity score provides an objective tool for assessing disease severity, both at diagnosis and during follow-up and treatment.

KL-6: marker for pulmonary involvement in Langerhans cell histiocytosis in infants

The purpose of this study was to investigate serum KL-6 levels in an infant with Langerhans cell histiocytosis (LCH) and pulmonary involvement. The histologic diagnosis of LCH was established by skin biopsy. Imaging of the chest confirmed marked interstitial shadowing throughout both lung fields. Acutely, serum KL-6 was elevated to 9,400 U/mL. Following induction chemotherapy, clinical manifestations of LCH improved and the levels of serum KL-6 returned to within normal limits. During the maintenance therapy phase, there was a resurgence of the LCH, but without involvement of the lungs, and the levels of KL-6 remained normal. The authors conclude that KL-6 may be a useful marker for pulmonary involvement in infants with LCH.