Evaluation and treatment of Langerhans cell histiocytosis patients with central nervous system abnormalities: Current views and new vistas

Approach to the Patient: From Endocrinopathy to the Diagnosis of a Histiocytic Disorder

Endocrinopathies are frequently the initial presentation of histiocytic neoplasms, which are rare hematologic disorders affecting multiple organ systems. Langerhans cell histiocytosis and Erdheim-Chester disease are 2 such disorders known to infiltrate the hypothalamus and/or pituitary gland, leading to arginine vasopressin deficiency (AVP-D) and anterior pituitary dysfunction (APD) in 20% to 30% of cases, often as the first manifestation. Conversely, histiocytic disorders account for a notable proportion (10-15%) of all pituitary stalk lesions. The diagnosis of histiocytoses is often delayed in such cases due to the nonspecific presentation of endocrinopathies and pituitary involvement. Consequently, endocrinologists are at the frontline and uniquely positioned to achieve early diagnosis by recognizing the varied nonendocrine features of these disorders. This article provides an overview of the endocrine manifestations of histiocytic disorders and presents a simplified algorithm to guide the diagnostic workup in cases presenting with "idiopathic" AVP-D or APD. Such cases should be evaluated for histiocytic neoplasms with additional imaging studies and biopsies of suspected disease sites. If no disease site beyond the pituitary is identified, the risks and benefits of a pituitary stalk lesion biopsy must be carefully considered. While treatments of histiocytic neoplasms are highly efficacious, endocrinopathies are considered permanent and require long-term hormone replacement. It remains unclear whether early diagnosis and novel targeted therapies can reverse these endocrine disorders. Therefore, the role of the endocrinologist role is critical in the diagnosis and management of these rare diseases.

Unraveling Histiocytic Disorders: Two Cases From Resource-Limited Settings

Histiocytic disorders include a range of uncommon illnesses marked by the buildup of cells that have developed into macrophages, dendritic cells, or monocytes in diverse tissues and organs. Over 100 distinct subtypes have been documented, exhibiting a diverse array of clinical symptoms, presentations, and histologic features that can be confused with other clinical conditions leading to delayed diagnosis. They affect both children and adults, generating a variety of clinical symptoms that can be limited to one position, numerous areas within one system, or affect many systems in the body. We provide our experiences handling two cases of histiocytic disease in underdeveloped countries where targeted treatment choices are unavailable. The first patient was a 32-year-old female with polyuria, skin lesions, and macroadenoma on MRI. Histopathological and immune-histochemical assessment of skin lesions confirmed the diagnosis of Langerhans cell histiocytosis. The patient responded well to steroids and oral and intrathecal methotrexate. The second patient was a 38-year-old male with recurrent skin lesions followed by retro-orbital discomfort and proptosis. The retro-orbital mass was surgically excised followed by a recurrence a few months later. Histopathological and immune-histochemical assessment confirmed the diagnosis of extranodal Rosai-Dorfman disease. He showed a partial response to methotrexate followed by a remarkable response to rituximab. Because of the wide variety of clinical symptoms, the diversity of experts engaged in assessing and treating these patients, and the scarcity of cases accessible, there is still a need to develop an evidence-based technique for evaluating and treating this complicated disease, especially in resource-limited settings.

A multidisciplinary non-invasive approach to monitor response to intravenous immunoglobulin treatment in neurodegenerative Langerhans cell histiocytosis: a real-world study

Aims

Early detection and treatment of neurodegenerative Langerhans cell histiocytosis (ND-LCH) have been suggested to prevent neurodegenerative progression. The aim of the study is to validate a standardized multidisciplinary diagnostic work-up to monitor the intravenous immunoglobulins (IVIG) treatment response and the natural course of the disease in untreated patients.

Methods

Patients with abnormal somatosensory evoked potentials (SEPs) received monthly 0.5 g/kg IVIG. The diagnostic protocol included structural 3T MRI, neurological examination, brainstem auditory evoked potentials (BAEPs) and SEPs.

Results

Twenty-two patients were followed for 5.2 years (median) from the first MRI evidence of ND-LCH. Eleven patients received IVIG for 1.7 years (median). At treatment start neurological examination was abnormal in 10 patients, of whom two had severe clinical impairment and four had abnormal BAEPs. At last follow-up, 1/11 remained stable and 7/11 improved, while worsening of neurological or neurophysiological findings, or both, occurred in 3/11. Risk factors for worsening were a severe clinical or MRI ND-LCH at treatment initiation and prolonged exposure to LCH. Of the 11 untreated patients, none improved and three worsened.

Conclusions

Using a standardized diagnostic protocol, we demonstrated that IVIG treatment can lead to clinical stabilization or improvement in all pauci-symptomatic patients with an MRI grading of less than 4.

Langerhans cell histiocytosis: NACHO update on progress, chaos, and opportunity on the path to rational cures

Langerhans cell histiocytosis (LCH) is a myeloid neoplastic disorder characterized by lesions with CD1a-positive/Langerin (CD207)-positive histiocytes and inflammatory infiltrate that can cause local tissue damage and systemic inflammation. Clinical presentations range from single lesions with minimal impact to life-threatening disseminated disease. Therapy for systemic LCH has been established through serial trials empirically testing different chemotherapy agents and durations of therapy. However, fewer than 50% of patients who have disseminated disease are cured with the current standard-of-care vinblastine/prednisone/(mercaptopurine), and treatment failure is associated with long-term morbidity, including the risk of LCH-associated neurodegeneration. Historically, the nature of LCH-whether a reactive condition versus a neoplastic/malignant condition-was uncertain. Over the past 15 years, seminal discoveries have broadly defined LCH pathogenesis; specifically, activating mitogen-activated protein kinase pathway mutations (most frequently, BRAFV600E) in myeloid precursors drive lesion formation. LCH therefore is a clonal neoplastic disorder, although secondary inflammatory features contribute to the disease. These paradigm-changing insights offer a promise of rational cures for patients based on individual mutations, clonal reservoirs, and extent of disease. However, the pace of clinical trial development behind lags the kinetics of translational discovery. In this review, the authors discuss the current understanding of LCH biology, clinical characteristics, therapeutic strategies, and opportunities to improve outcomes for every patient through coordinated agent prioritization and clinical trial efforts.

Juvenile xanthogranuloma manifesting with LCH-associated neurodegenerative disease-like radiological findings

Here, we describe two patients with juvenile xanthogranuloma (JXG) manifesting with Langerhans cell histiocytosis (LCH)-associated neurodegenerative disease (ND)-like radiological findings. One patient showed typical radiological abnormalities at onset, which worsened with progressing central nervous system symptoms 7 years after LCH-oriented chemotherapy. Another showed spontaneous regression of clinical symptoms, with a transient radiological change 1 year after salvage chemotherapy for recurrence of JXG. These data regarding JXG-associated ND will facilitate future investigation of the disease, as well as development of therapeutic interventions.

Clofarabine monotherapy in aggressive, relapsed and refractory Langerhans cell histiocytosis

Over 50% of patients with systemic LCH are not cured with front-line therapies, and data to guide salvage options are limited. We describe 58 patients with LCH who were treated with clofarabine. Clofarabine monotherapy was active against LCH in this cohort, including heavily pretreated patients with a systemic objective response rate of 92.6%, higher in children (93.8%) than adults (83.3%). BRAFV600E+ variant allele frequency in peripheral blood is correlated with clinical responses. Prospective multicentre trials are warranted to determine optimal dosing, long-term efficacy, late toxicities, relative cost and patient-reported outcomes of clofarabine compared to alternative LCH salvage therapy strategies.

Clinical, radiological and molecular responses to combination chemotherapy with MAPK pathway inhibition in relapsed and refractory Langerhans cell histiocytosis

Optimal therapeutic approaches for advanced Langerhans cell histiocytosis (LCH) are not known. We assessed the safety and efficacy of combined chemotherapy with MAPK pathway inhibition in 10 patients with refractory systemic disease and/or LCH-associated neurodegeneration. Overall response rate was 9/10 (90%) for the entire cohort: 5/5 (100%) for patients with systemic disease and 6/7 (86%) for patients with central nervous system disease. BRAFV600E+ peripheral blood fraction decreased in 5/6 (83%). Toxicities included fever, skin rash, myalgias, neuropathy, cytopenias and hypocalcaemia. Prospective trials are required to optimize combination strategies, determine potential to achieve cure and compare outcomes to chemotherapy or MAPK inhibitor monotherapy.

A novel classification for guiding the surgical approach for cranio-orbital lesions: a single institution case series of 45 cases and a literature review

We aim to share our experience of the removal of cranio-orbital lesions (COLs) and propose a novel classification to guide the tailored approach selection. We retrospectively reviewed 45 consecutive patients with COLs who underwent surgery performed by the same neurosurgeon between November 2010 and November 2022. The surgical approach was selected according to the anatomical region classification of the COLs. For lesions limited to space A (lateral superior orbital fissure, SOF), the pterion or extended pterion approach (PA or EPA) was used. For lesions limited to space B (extraconal compartment medial SOF, and cavernous sinus CS) and C (intraconal compartment, medial SOF, and CS), the pretemporal transcavernous approach (PTCA) was used. For lesions limited to space D (intraconal compartment and optic canals), the subfrontal approach (SA) was used. For lesions extending into the infratemporal fossa (ITF), the cranio-orbito-zygomatic approach (COZA) was used. For lesions involving pterygopalatine fossa (PPF), the endoscopic transnasal approach (ETNA) was used. We analyzed the clinical manifestations, imaging data, surgical approaches, surgical outcomes, neurological outcomes, and follow-up data. Gross total resection was performed in 35 patients (35/45, 77.8%). SA, PA, EPA, PTCA, COZA, and ETNA were performed in 9, 9, 10, 10, 6, and 1 case(s), respectively. Progression of the residual tumor was observed in 6 cases (1 adenoid cystic carcinoma and 5 meningiomas). Surgical approach selection plays a vital role in patient prognosis. This novel classification based on the involvement of anatomic space could help surgeons select an appropriate approach to remove the COLs.

Cerebellar peduncle damage in Langerhans cell histiocytosis-associated neurodegenerative disease revealed by diffusion tensor imaging

PURPOSE

To confirm the hypothesis that brain white matter damage is involved in the pathogenesis and disease progression of Langerhans cell histiocytosis (LCH)-associated neurodegenerative disease (ND), we aimed to analyze pediatric patients with LCH using diffusion tensor imaging (DTI).

METHODS

We enrolled 33 patients with LCH and obtained 33 DTI datasets. Using DTI-based tractography, fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD) were measured in the cerebral and cerebellar white matter tracts. The participants were divided into three groups-non-ND, ND without clinical symptoms (r-ND), and ND with clinical symptoms (c-ND)-according to their clinical status during the examination with DTI. We compared the DTI parameters in white matter tracts were compared among the three groups.

RESULTS

In the order of non-ND, r-ND, and c-ND groups, the FA in superior cerebellar peduncle (SCP) and middle cerebellar peduncle (MCP) significantly decreased, the ADC, AD, and RD of MCP, and the RD of SCP were significantly elevated (FA-SCP; p < 0.001, FA-MCP; p = 0.026, ADC-MCP; p < 0.001, AD-MCP; p = 0.002, RD-MCP; p = 0.003, and RD-SCP; p = 0.018). Furthermore, in the simple linear regression analysis, the FA, ADC, AD, and RD values in the MCP and the FA value in the SCP were significantly influenced by the presence of neurological symptoms and ND findings on MRI (all p < 0.001).

CONCLUSION

In LCH-ND, we identified microstructural damage in the SCP and MCP. DTI parameters in these tracts may help monitor LCH-ND; therefore, future studies are required to validate these results in a large cohort.

Circulating senescent myeloid cells infiltrate the brain and cause neurodegeneration in histiocytic disorders

Neurodegenerative diseases (ND) are characterized by progressive loss of neuronal function. Mechanisms of ND pathogenesis are incompletely understood, hampering the development of effective therapies. Langerhans cell histiocytosis (LCH) is an inflammatory neoplastic disorder caused by hematopoietic progenitors expressing mitogen-activated protein kinase (MAPK)-activating mutations that differentiate into senescent myeloid cells that drive lesion formation. Some individuals with LCH subsequently develop progressive and incurable neurodegeneration (LCH-ND). Here, we showed that LCH-ND was caused by myeloid cells that were clonal with peripheral LCH cells. Circulating BRAFV600E+ myeloid cells caused the breakdown of the blood-brain barrier (BBB), enhancing migration into the brain parenchyma where they differentiated into senescent, inflammatory CD11a+ macrophages that accumulated in the brainstem and cerebellum. Blocking MAPK activity and senescence programs reduced peripheral inflammation, brain parenchymal infiltration, neuroinflammation, neuronal damage and improved neurological outcome in preclinical LCH-ND. MAPK activation and senescence programs in circulating myeloid cells represent targetable mechanisms of LCH-ND.

Langerhans cell histiocytosis: promises and caveats of targeted therapies in high-risk and CNS disease

Langerhans cell histiocytosis (LCH) is a rare myeloid neoplasm driven by activating mutations in the MAPK pathway, most commonly BRAF-V600E and MAP2K1. It affects children and adults, with a wide spectrum of clinical presentations ranging from self-limited to multisystem (MS) life-threatening forms. LCH is defined by the accumulation of CD1a+/CD207+ cells in different organs, and patients with liver, spleen, or hematopoietic system involvement have a higher risk of mortality. Patients with neurodegeneration (ND) have devastating outcomes and are resistant to systemic therapies. MS-LCH is treated with risk-adapted therapy, but many patients require multiple salvage regimens that are myelosuppressive and expensive. MAPK inhibitors are increasingly being used, but most patients relapse upon discontinuation of therapy. Here, we review the management of central nervous system disease and how novel cerebrospinal fluid biomarkers might predict patients at high risk of ND who could benefit from early MAPK inhibition. Further, we discuss treatment strategies for refractory/relapsed (R/R) LCH, with a focus on MAPK inhibitors' efficacy and challenges (ie, the unknown): long-term toxicity in children, optimal duration, if they are curative, whether it is safe to combine them with chemotherapy, and their high price tag. Lastly, emerging strategies, such as the new panRAF inhibitor (Day 101) in patients with R/R LCH, ERK1/2 or CSF1R inhibition in patients with MEK1/2 inhibitor resistance, and targeting the microenvironment (checkpoint plus MEK inhibition) or senescent cells (mTOR or BCL-XL inhibitors) in R/R patients, are also examined.

Long-term outcomes among adults with Langerhans cell histiocytosis

Advances in the treatment of Langerhans cell histiocytosis (LCH) have resulted in a growing survivor population. There is a lack of data on long-term outcomes among adults with LCH. We conducted a retrospective record review of 219 adults (aged ≥18 years) with LCH. Most common presentation was multisystem (34.2%), followed by single-system pulmonary (32%), unifocal (28.3%), and single-system multifocal (5.5%) LCH. Risk organ involvement (the liver, spleen, or bone marrow) was seen in 8.7% of cases, and 40 of 88 (45.5%) tested cases were BRAFV600E. At a median follow-up of 74 months, 5-year progression-free survival (PFS) was 58.3% and estimated median PFS was 83 months. Median overall survival (OS) was not reached; 5- and 10-year OS rates were 88.7% and 74.5%, respectively. Risk organ involvement was associated with worse PFS (hazard ratio [HR], 4.5) and OS (HR, 10.8). BRAFV600E was not associated with risk organ involvement or survival. When compared with matched unaffected US population, individuals with LCH had a significantly higher risk of overall mortality (standardized mortality ratio [SMR], 2.66), specifically among those aged <55 years at diagnosis (SMR, 5.94) and those with multisystem disease (SMR, 4.12). Second cancers occurred in 16.4% cases, including diverse hematologic and solid organ malignancies. LCH-associated deaths constituted 36.1% of deaths and occurred within 5 years of diagnosis. After 5 years, non-LCH causes of death, including second cancers, chronic obstructive pulmonary disease, and cardiovascular diseases, predominated. Our study highlights, to our knowledge, for the first time, that adults with LCH experience early and late mortality from non-LCH causes and the need for development of targeted survivorship programs to improve outcomes.

Circulating senescent myeloid cells drive blood brain barrier breakdown and neurodegeneration

Neurodegenerative diseases (ND) are characterized by progressive loss of neuronal function. Mechanisms of ND pathogenesis are incompletely understood, hampering the development of effective therapies. Langerhans cell histiocytosis (LCH) is an inflammatory neoplastic disorder caused by hematopoietic progenitors expressing MAPK activating mutations that differentiate into senescent myeloid cells that drive lesion formation. Some patients with LCH subsequently develop progressive and incurable neurodegeneration (LCH-ND). Here, we show that LCH-ND is caused by myeloid cells that are clonal with peripheral LCH cells. We discovered that circulating BRAF V600E + myeloid cells cause the breakdown of the blood-brain barrier (BBB), enhancing migration into the brain parenchyma where they differentiate into senescent, inflammatory CD11a + macrophages that accumulate in the brainstem and cerebellum. Blocking MAPK activity and senescence programs reduced parenchymal infiltration, neuroinflammation, neuronal damage and improved neurological outcome in preclinical LCH-ND. MAPK activation and senescence programs in circulating myeloid cells represent novel and targetable mechanisms of ND.

[Histiocytosis]

Histiocytosis is a group of rare diseases characterized by inflammation and accumulation of cells derived from monocytes and macrophages in different tissues. The symptoms are highly variable, from mild forms with involvement of a single organ to severe multisystem forms that can be life compromising. The diagnosis of histiocytosis is based on the clinic, radiological findings and pathological anatomy. A biopsy of the affected tissue is recommended in all cases as it may have therapeutic implications. During the last decade, some mutations have been identified in the affected tissue that condition activation of the MAPK/ERK and PI3K/AKT pathway, in a variable proportion depending on the type of histiocytosis. In this review we mainly focus on Langerhans Cell Histiocytosis, Erdheim-Chester Disease and Rosai-Dorfman Disease.

Neurological Manifestations of Histiocytic Disorders

PURPOSE OF REVIEW

Histiocytic disorders, including Erdheim-Chester disease (ECD), Langerhans cell histiocytosis (LCH), and Rosai-Dorfman disease (RDD), are rare neoplasms that may present with a spectrum of neurologic involvement. Diagnostic delay is common due to heterogeneity in presentation and challenging pathology.

RECENT FINDINGS

Recent advances in the treatment of these diseases targeted towards mutations in the MAP kinase pathway have led to an improved prognosis in these patients with neurologic involvement. It is critical for clinicians to have a high index of suspicion to allow for early targeted treatment and optimize neurologic outcomes. A systematic approach to diagnosis is presented in this article to allow for accurate diagnosis of these rare diseases.

Treatment of Langerhans Cell Histiocytosis and Histiocytic Disorders: A Focus on MAPK Pathway Inhibitors

Histiocytic disorders are rare diseases defined by the clonal accumulation of a macrophage or dendritic cell origin. These disorders include Langerhans cell histiocytosis, Erdheim-Chester disease, juvenile xanthogranuloma, malignant histiocytoses, and Rosai-Dorfman-Destombes disease. These histiocytic disorders are a diverse group of disorders with different presentations, management, and prognosis. This review focuses on these histiocytic disorders and the role of pathological ERK signaling due to somatic mutations in the mitogen--activated protein kinase (MAPK) pathway. Over the last decade, there has been growing awareness of the MAPK pathway being a key driver in many histiocytic disorders, which has led to successful treatment with targeted therapies, in particular, BRAF inhibitors and MEK inhibitors.

Langerhans Cell Histiocytosis in Children: Literature Review

Relevant information on Langerhans cell histiocytosis development and course in children is presented. The current concepts of disease pathogenesis, principles of its severity evaluation, patients stratification into risk groups, as well as of clinical course features are described. Modern approaches to the disease treatment via targeted therapy are summarized and analyzed. 

Paediatric Strategy Forum for medicinal product development in mitogen-activated protein kinase pathway inhibitors: ACCELERATE in collaboration with the European Medicines Agency with participation of the Food and Drug Administration

As the mitogen-activated protein kinase (MAPK) signalling pathway is activated in many paediatric cancers, it is an important therapeutic target. Currently, a range of targeted MAPK pathway inhibitors are being developed in adults. However, MAPK signals through many cascades and feedback loops and perturbing the MAPK pathway may have substantial influence on other pathways as well as normal development. In view of these issues, the ninth Paediatric Strategy Forum focused on MAPK inhibitors. Development of MAPK pathway inhibitors to date has been predominantly driven by adult indications such as malignant melanoma. However, these inhibitors may also target unmet needs in paediatric low-grade gliomas, high-grade gliomas, Langerhans cell histiocytosis, juvenile myelomonocytic leukaemia and several other paediatric conditions. Although MAPK inhibitors have demonstrated activity in paediatric cancer, the response rates and duration of responses needs improvement and better documentation. The rapid development and evaluation of combination approaches, based on a deep understanding of biology, is required to optimise responses and to avoid paradoxical tumour growth and other unintended consequences including severe toxicity. Better inhibitors with higher central nervous systempenetration for primary brain tumours and cancers with a propensity for central nervous system metastases need to be studied to determine if they are more effective than agents currently being used, and the optimum duration of therapy with MAPK inhibition needs to be determined. Systematic and coordinated clinical investigations to inform future treatment strategies with MAPK inhibitors, rather than use outside of clinical trials, are needed to fully assess the risks and benefits of these single agents and combination strategies in both front-line and in the refractory/relapse settings. Platform trials could address the investigation of multiple similar products and combinations. Accelerating the introduction of MAPK inhibitors into front-line paediatric studies is a priority, as is ensuring that these studies generate data appropriate for scientific and regulatory purposes. Early discussions with regulators are crucial, particularly if external controls are considered as randomised control trials in small patient populations can be challenging. Functional end-points specific to the populations in which they are studied, such as visual acuity, motor and neuro psychological function are important, as these outcomes are often more reflective of benefit for lower grade tumours (such as paediatric low-grade glioma and plexiform neurofibroma) and should be included in initial study designs for paediatric low-grade glioma. Early prospective discussions and agreements with regulators are necessary. Long-term follow-up of patients receiving MAPK inhibitors is crucial in view of their prolonged administration and the important involvement of this pathway in normal development. Further rational development, with a detailed understanding of biology of this class of products, is crucial to ensure they provide optimal benefit while minimising toxicity to children and adolescents with cancer.

Neuroimaging in Pediatric Patients with Juvenile Xanthogranuloma of the CNS

BACKGROUND AND PURPOSE

Juvenile xanthogranuloma is a rare clonal, myeloid, neoplastic disorder. Typically, juvenile xanthogranuloma is a self-limited disorder of infancy, often presenting as a solitary red-brown or yellow skin papule/nodule. A small subset of patients present with extracutaneous, systemic juvenile xanthogranuloma, which may include the CNS. The goal of this retrospective study was to evaluate and categorize the neuroimaging findings in a representative cohort of pediatric patients with CNS juvenile xanthogranuloma.

MATERIALS AND METHODS

The brain and/or spine MR imaging data of 14 pediatric patients with pathology-proven juvenile xanthogranuloma were categorized and evaluated for the location; the signal intensity of xanthogranulomas on T1WI, T2WI, DWI, and a matching ADC map for the pattern and degree of contrast enhancement; and the presence of perilesional edema, cysts, or necrosis.

RESULTS

Fourteen pediatric patients (8 girls, 6 boys; mean age, 84 months) were included in the study. Patients presented with a wide variety of different symptoms, including headache, seizure, ataxia, strabismus, hearing loss, facial paresis, and diabetes insipidus. Juvenile xanthogranuloma lesions were identified in a number of different sites, including supra- and infratentorial as well as intracranial and spinal leptomeningeal. Five patients were categorized into the neuroradiologic pattern unifocal CNS juvenile xanthogranuloma; 8, into multifocal CNS juvenile xanthogranuloma; and 1, into multifocal CNS juvenile xanthogranuloma with intracranial and spinal leptomeningeal disease. In most cases, xanthogranulomas were small-to-medium intra-axial masses with isointense signal on T1WI (compared with cortical GM), iso- or hyperintense signal on T2WI, had restricted diffusion and perilesional edema. Almost all xanthogranulomas showed avid contrast enhancement. However, we also identified less common patterns with large lesions, nonenhancing lesions, or leptomeningeal disease. Four cases had an additional CT available. On CT, all xanthogranulomas were homogeneously hyperdense (solid component) without evident calcifications.

CONCLUSIONS

CNS juvenile xanthogranuloma may demonstrate heterogeneous neuroimaging appearances potentially mimicking other diseases, such as primary brain neoplasms, metastatic disease, lymphoma and leukemia, other histiocytic disorders, infections, or granulomatous diseases.

Histiocytic Disorders of Childhood

Histiocytic disorders of childhood represent a wide spectrum of conditions that share the common histologic feature of activated or transformed "histiocytes." Langerhans cell histiocytosis (LCH) is the most common, with an incidence of approximately 5 per million children. LCH may be difficult to distinguish from more ubiquitous causes of skin rashes, bone pain, or fever. Current chemotherapy fails to cure more than 50% of children with multifocal disease, and treatment failure is associated with increased risks of long-term sequelae. Somatic activating mitogen-activated protein kinase (MAPK) pathway-activating mutations (most often BRAFV600E) have been identified in hematopoietic precursors in patients with LCH. Opportunities to improve outcomes with targeted therapies are under investigation. Juvenile xanthogranuloma (JXG) and Rosai-Dorfman disease (RDD) are less common than LCH and are distinguished by specific histologic and clinical features. Recurrent MAPK pathway gene mutations are also identified in JXG and RDD. In many cases, these conditions spontaneously resolve, but disseminated disease can be fatal. Although there has been historic debate regarding the nature of these conditions as inflammatory versus neoplastic, LCH, JXG, and RDD are now considered myeloid neoplastic disorders. In contrast, hemophagocytic lymphohistiocytosis (HLH) is clearly a disorder of immune dysregulation. HLH is characterized by extreme immune activation driven by hyperactivated T cells. HLH arises in approximately 1 child per million and is nearly universally fatal without prompt recognition and immune suppression. Outcomes of treated children are poor, with approximately 60% survival. Emapalumab, which targets interferon-γ signaling, was recently approved for patients with recurrent or refractory HLH, and additional cytokine-directed therapies are under investigation.

Socio-behavioral dysfunction in disorders of hypothalamic-pituitary involvement: The potential role of disease-induced oxytocin and vasopressin signaling deficits

Disorders involving hypothalamic and pituitary (HPIT) structures-including craniopharyngioma, Langerhans cell histiocytosis, and intracranial germ cell tumors-can disrupt brain and endocrine function. An area of emerging clinical concern in patients with these disorders is the co-occurring socio-behavioral dysfunction that persists after standard hormone replacement therapy. Although the two neuropeptides most implicated in mammalian social functioning (oxytocin and arginine vasopressin) are of hypothalamic origin, little is known about how disease-induced damage to HPIT structures may disrupt neuropeptide signaling and, in turn, impact patients' socio-behavioral functioning. Here we provide a clinical primer on disorders of HPIT involvement and a review of neuropeptide signaling and socio-behavioral functioning in relevant animal models and patient populations. This collective evidence suggests that neuropeptide signaling disruptions contribute to socio-behavioral deficits experienced by patients with disorders of HPIT involvement. A better understanding of the biological underpinnings of patients' socio-behavioral symptoms is now needed to enable the development of the first targeted pharmacological strategies by which to manage patients' socio-behavioral dysfunction.

Langerhans cell histiocytosis. Advances in pathogenesis and clinical practice

Langerhans cell histiocytosis (LCH) is a type of myeloid neoplasia that can affect different organs or tissues and exhibits substantial variability in its clinical presentation and biological behaviour, so it may mimic different diseases. Performance of different clinical assessments and laboratory and imaging tests is recommended to determine the extent of involvement, which may be of a single location or multisystemic, and the presence or absence of dysfunction in risk organs, such as the haematopoietic system, liver and spleen. The diagnosis must be confirmed by histological examination of a biopsy sample. Molecular tests have identified mutations in the mitogen-activated protein kinase (MAPK) pathway, which has expanded treatment options. The diagnosis is complex and there is controversy regarding the management of certain cases. Treatment recommendations depend on the location of the lesions and the extent of involvement. International collaborative studies have demonstrated the effectiveness of prolonged combination therapies such as vinblastine and prednisone in severe or multisystemic forms, and anti-inflammatory drugs such as indomethacin and other cytostatic combinations have proven beneficial. Langerhans cell histiocytosis is a good example of the importance of precision medicine and the benefit of identifying molecular targets, common to different neoplasms, to develop new therapies. MAPK pathway inhibitors offer an alternative treatment option in refractory cases and neurodegenerative forms of LCH. Molecular testing can contribute to the prognosis, treatment and follow-up of LCH, especially in severe forms of disease.

Neuroimaging in cerebellar ataxia in childhood: A review

Ataxia is one of the most common pediatric movement disorders and can be caused by a large number of congenital and acquired diseases affecting the cerebellum or the vestibular or sensory system. It is mainly characterized by gait abnormalities, dysmetria, intention tremor, dysdiadochokinesia, dysarthria, and nystagmus. In young children, ataxia may manifest as the inability or refusal to walk. The diagnostic approach begins with a careful clinical history including the temporal evolution of ataxia and the inquiry of additional symptoms, is followed by a meticulous physical examination, and, depending on the results, is complemented by laboratory assays, electroencephalography, nerve conduction velocity, lumbar puncture, toxicology screening, genetic testing, and neuroimaging. Neuroimaging plays a pivotal role in either providing the final diagnosis, narrowing the differential diagnosis, or planning targeted further workup. In this review, we will focus on the most common form of ataxia in childhood, cerebellar ataxia (CA). We will discuss and summarize the neuroimaging findings of either the most common or the most important causes of CA in childhood or present causes of pediatric CA with pathognomonic findings on MRI. The various pediatric CAs will be categorized and presented according to (a) the cause of ataxia (acquired/disruptive vs. inherited/genetic) and (b) the temporal evolution of symptoms (acute/subacute, chronic, progressive, nonprogressive, and recurrent). In addition, several illustrative cases with their key imaging findings will be presented.

Infantile-Onset Isolated Neurohypophyseal Langerhans Cell Histiocytosis with Central Diabetes Insipidus: A Case Report

Central diabetes insipidus (CDI) is a rare disease in children and has a variety of etiologies. The major causes of CDI with pituitary stalk thickening (PST) are germinoma, Langerhans cell histiocytosis (LCH), and Lymphocytic infundibulo-neurohypophysitis, which are difficult to differentiate by imaging and require pathological diagnosis. We report a case of infantile-onset isolated neurohypophyseal LCH diagnosed by pathological findings. A 2-year-old girl presented with polydipsia and polyuria. CDI was diagnosed and treatment with oral desmopressin was initiated. Magnetic resonance imaging (MRI) of the head showed PST and absence of high-signal intensity of posterior pituitary on T1-weighted images. Follow-up MRI scans showed that the tumor mass was gradually increasing and extending posteriorly toward the area near the mamillary body. Simultaneously, anterior pituitary dysfunction was observed. She underwent a biopsy of the PST and LCH was diagnosed by immunohistochemical analysis. DNA analysis showed no BRAF V600E mutation. Monotherapy with 2-Chlorodeoxyadenosine reduced the tumor size but did not improve pituitary function. Isolated neurohypophyseal LCH should be considered in infantile-onset cases of CDI with PST. 2-CdA treatment resulted in rapid PST shrinkage. Further cases are needed to determine whether early diagnosis and treatment can prevent anterior pituitary dysfunction.

International expert consensus recommendations for the diagnosis and treatment of Langerhans cell histiocytosis in adults

Langerhans cell histiocytosis (LCH) can affect children and adults with a wide variety of clinical manifestations, including unifocal, single-system multifocal, single-system pulmonary (smoking-associated), or multisystem disease. The existing paradigms in the management of LCH in adults are mostly derived from the pediatric literature. Over the last decade, the discovery of clonality and MAPK-ERK pathway mutations in most cases led to the recognition of LCH as a hematopoietic neoplasm, opening the doors for treatment with targeted therapies. These advances have necessitated an update of the existing recommendations for the diagnosis and treatment of LCH in adults. This document presents consensus recommendations that resulted from the discussions at the annual Histiocyte Society meeting in 2019, encompassing clinical features, classification, diagnostic criteria, treatment algorithm, and response assessment for adults with LCH. The recommendations favor the use of 18F-Fluorodeoxyglucose positron emission tomography-based imaging for staging and response assessment in the majority of cases. Most adults with unifocal disease may be cured by local therapies, while the first-line treatment for single-system pulmonary LCH remains smoking cessation. Among patients not amenable or unresponsive to these treatments and/or have multifocal and multisystem disease, systemic treatments are recommended. Preferred systemic treatments in adults with LCH include cladribine or cytarabine, with the emerging role of targeted (BRAF and MEK inhibitor) therapies. Despite documented responses to treatments, many patients struggle with a high symptom burden from pain, fatigue, and mood disorders that should be acknowledged and managed appropriately.

Rosai-Dorfman-Destombes disease of the nervous system: a systematic literature review

BACKGROUND

Rosai-Dorfman-Destombes disease (RDD) is a rare histiocytic disorder with heterogeneous clinical manifestations and rare neurologic involvement. The existing clinical literature about neurologic RDD has yet to be critically examined.

METHODS

We performed a four-database English-language systematic literature search for cases of RDD neurohistiocytosis, excluding secondary literature. Individual patient data for neurologic symptoms, disease sites, treatments, and responses were captured. Responses to first-line and second-line surgical interventions, post-surgical radiotherapy, and systemic therapies were analyzed.

RESULTS

Among 4769 articles yielded by literature search, 154 articles were fully reviewed, containing data on 224 patients with neurologic RDD. 128 (83.1%) articles were single case reports. 149 (66.5%) patients were male, 74 (33.5%) female, with a median age of 37.6 years (range 2-79). Presenting neurologic symptoms included headache (45.1%), focal neurological deficits (32.6%), visual symptoms (32.1%), and seizures (24.6%). RDD involvement was multifocal in 32 (14.3%) cases. First-line treatment involved resection in 200 (89.6%) patients, with subsequent progression in 52 (26%), including 41 (78.8%) with unifocal disease. No difference was observed in progression-free survival comparing post-operative radiotherapy to no radiotherapy following partial resection. Chemotherapy given alone as first-line treatment led to complete or partial response in 3/7(43%) patients. Second-line treatments led to complete or partial response in 18/37(37.5%) patients. Mutational data were reported on 10 patients (4.46%).

CONCLUSIONS

This review highlights the limited published data about neurologic RDD, which presents with varied symptomatology and outcome. Further study is needed about its mutational landscape, and more effective therapies are needed for recurrent and refractory disease.

Second-line regimen for CNS-involved pediatric Langerhans cell histiocytosis

PURPOSE

Langerhans cell histiocytosis (LCH) can affect any organ. Central nervous system (CNS) involvement is rare, and its management is poorly understood. This study aimed to analyze the clinical response and prognosis of pediatric LCH with central diabetes insipidus (CDI) treated with second-line therapy with cytarabine (Ara-c), cladribine (2-cdA), dexamethasone, and vindesine.

METHODS

This retrospective case series study included pediatric LCH with CDI treated at Beijing Children's Hospital affiliated with Capital Medical University (11/2012-01/2018). After the first-line 2009-LCH regimen, patients with active disease/worse response, relapse, or no significant improvement in risk organs, pituitary, or lung were given the second-line therapy. Baseline characteristics, clinical response and adverse reactions were observed.

RESULTS

Twenty-six children with CDI and disappearance of hyperintensity in the posterior pituitary were included. They received "Regimen A" Ara-c + dexamethasone + vindesine (n = 7) or "Regimen B" Ara-c + dexamethasone + vindesine + 2-cdA (n = 19) as second-line therapy. There were 14 patients with CDI but without pituitary stalk thickening (PST) and 12 with CDI and PST. In patients with CDI alone, 4/4 patients receiving Regimen A and 3/10 receiving Regimen B improved. All patients with CDI and PST showed improvement for PST. The reappearance of hyperintensity at the posterior pituitary was observed in 10 patients with CDI. All 26 children were alive after a median follow-up of 40.5 months. There were no chemotherapy-related deaths.

CONCLUSION

A combined therapy with Ara-c, 2-cdA, dexamethasone, and vindesine could partially alleviate pituitary disease conditions in pediatric LCH with CNS involvement, with good tolerance.

Clinical features and treatment of Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is caused by the expansion of CD1a+/CD207+ cells and is characterised by a wide spectrum of organ involvement and dysfunction, affecting all ages. While almost all organs and systems can be affected, only the involvement and dysfunction of liver, spleen, and haematopoietic system influence survival. The LCH pathogenic cells are defined by universal activation of the mitogen-activated protein kinase (MAPK) signalling pathway. The most common alteration is a somatic BRAFV600E mutation, which is present in approximately two-thirds of the cases, followed by MAP2K1 mutations. Treatment of LCH is risk-adapted; patients with single lesions may respond well to local treatment, whereas patients with multi-system disease require systemic chemotherapy. While survival for patients without organ dysfunction is excellent, mortality rates for patients with organ dysfunction may reach 20%. Despite progress made in the treatment of LCH, disease reactivation rates remain above 30%, and standard second-line treatment has yet to be established. Long-term effects, including neuroendocrine dysfunction and neurodegeneration, represent a major challenge for survivors. Treatment with BRAF or MEK inhibitors results in immediate responses, but reactivations are very common after discontinuation. Their role as single agents and in combination with chemotherapy is being explored.

Histiocytosis and the nervous system: from diagnosis to targeted therapies

Histiocytoses are heterogeneous hematopoietic diseases characterized by the accumulation of CD68(+) cells with various admixed inflammatory infiltrates. The identification of the pivotal role of the mitogen-activated protein kinase (MAPK) pathway has opened new avenues of research and therapeutic approaches. We review the neurologic manifestations of 3 histiocytic disorders with frequent involvement of the brain and spine: Langerhans cell histiocytosis (LCH), Erdheim-Chester disease (ECD), and Rosai-Dorfman-Destombes disease (RDD). Central nervous system (CNS) manifestations occur in 10%-25% of LCH cases, with both tumorous or neurodegenerative forms. These subtypes differ by clinical and radiological presentation, pathogenesis, and prognosis. Tumorous or degenerative neurologic involvement occurs in 30%-40% of ECD patients and affects the hypothalamic-pituitary axis, meninges, and brain parenchyma. RDD lesions are typically tumorous with meningeal or parenchymal masses with strong contrast enhancement. Unlike LCH and ECD, neurodegenerative lesions or syndromes have not been described with RDD. Familiarity with principles of evaluation and treatment both shared among and distinct to each of these 3 diseases is critical for effective management. Refractory or disabling neurohistiocytic involvement should prompt the consideration for use of targeted kinase inhibitor therapies.

Discrepancies between F-18-FDG PET/CT findings and conventional imaging in Langerhans cell histiocytosis

BACKGROUND

Accurate risk stratification of Langerhans cell histiocytosis (LCH) is essential as management can range from conservative in single system, low risk for central nervous system (CNS) involvement lesions to intensive chemotherapy for multisystem or high-risk disease. Additionally, being able to differentiate metabolically active from inactive lesions is essential for both prognostic reasons and to avoid potentially unnecessary treatment.

METHODS

A retrospective review was performed on all patients with histopathology-confirmed LCH at Cincinnati Children's Hospital Medical Center (CCHMC) between 2009 and 2019.

RESULTS

One hundred seven positron emission tomography (PET)/computerized tomography (CT) images were included in the review. A discrepancy between PET/CT and conventional imaging occurred on 53 occasions. On 13 occasions, increased uptake was observed on PET in an area with no identifiable lesion on conventional imaging. On 40 occasions, lesions were found on conventional imaging where no increased uptake was observed on PET. On eight skeletal surveys, three other radiographs, four diagnostic CTs, five localization CTs, and one bone scan, no lesion was identified in an area with increased fluorodeoxyglucose (FDG) uptake. This occurred exclusively in bone. On nine skeletal surveys, one other radiograph, four diagnostic CTs, six localization CTs, 19 magnetic resonance imaging (MRI) scans, and one bone scan, a lesion was identified in a location without increased FDG uptake. This occurred in bone, CNS, and lungs.

CONCLUSION

F-18-FDG PET/CT is vital in the evaluation of LCH lesions given its ability to detect LCH lesions not detectable on conventional imaging modalities, as well as its ability to distinguish metabolically active from inactive disease. MRI and diagnostic CT are still useful adjunctive tests for identification of CNS and lung lesions.

Langerhans Cell Histiocytosis of the Orbit: Spectrum of Clinical and Imaging Findings

OBJECTIVE

To evaluate the clinical and imaging characteristics of orbital lesions of pediatric Langerhans cell histiocytosis (LCH).

STUDY DESIGN

A retrospective analysis of clinical data and central review of magnetic resonance imaging scans in patients with LCH, enrolled into one of the consecutive international trials LCH I-III, or submitted for a second opinion between 1994 and 2015.

RESULTS

Data from 31 children (34 involved orbits) were analyzed. Orbital LCH was the only disease manifestation in 15, part of a multifocal skeletal in 5, or a multisystem LCH in 11 patients. Orbital LCH was part of the initial disease presentation in 23 or developed at relapse in 8 cases. Orbital involvement was unilateral in 28 and bilateral in 3 patients (34 affected orbits). Proptosis was present in 9 patients. Frontal and zygomatic bone were most commonly affected. All orbital lesions were extraconal. Associated extraorbital imaging findings were dural tail sign in 19, neurodegeneration in 8, and hypothalamic-pituitary mass in 3 patients. Sixteen patients (52%) had at least 1 documented disease relapse. Permanent consequences were prominent proptosis in 1, diabetes insipidus in 8, growth hormone deficiency in 2, radiologic neurodegeneration in 8, and clinical neurodegeneration in 3 patients.

CONCLUSIONS

Predominantly unilateral orbital LCH can be the only disease manifestation or part of a disseminated disease. Orbital lesions in LCH are exclusively extraconal, typically located at the roof and the lateral wall of the orbit. The optimal treatment approach of unifocal LCH of the orbit remains controversial and warrants a prospective evaluation.

Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is caused by clonal expansion of myeloid precursors that differentiate into CD1a+/CD207+ cells in lesions that leads to a spectrum of organ involvement and dysfunction. The pathogenic cells are defined by constitutive activation of the MAPK signaling pathway. Treatment of LCH is risk-adapted: patients with single lesions may respond well to local treatment, whereas patients with multisystem disease require systemic therapy. Although survival rates for patients without organ dysfunction is excellent, mortality rates for patients with organ dysfunction may reach 20%. Despite progress made in the treatment of LCH, disease reactivation rates remain above 30%, and standard second-line treatment is yet to be established. Treatment failure is associated with increased risks for death and long-term morbidity, including LCH-associated neurodegeneration. Early case series report promising clinical responses in patients with relapsed and refractory LCH treated with BRAF or MEK inhibitors, although potential for this strategy to achieve cure remains uncertain.

Osteopontin is highly secreted in the cerebrospinal fluid of patient with posterior pituitary involvement in Langerhans cell histiocytosis

BACKGROUND

Langerhans cell histiocytosis (LCH) is a rare disease caused by clonal proliferation of CD1a⁺ CD207⁺ cells. Distinguishing pituitary involvement was essential in stratification and treatment of patients with LCH. The diagnosis of pituitary involvement is mainly dependent on hormone abnormalities in the anterior pituitary and magnetic resonance imaging (MRI) scanning in posterior pituitary. Diabetes insipidus (DI) is a serious sequelae and often occurred with pituitary involvement. It is reported that osteopontin (OPN) is highly secreted in the cerebrospinal fluid (CSF) of patients with neurodegenerative diseases in LCH (LCH-ND). However, patients with posterior pituitary involvement account for a larger portion in our hospital. Whether the OPN level could be an auxiliary diagnostic marker for the posterior pituitary involvement or not is still unknown.

METHODS

In our study, we collected CSF samples of 57 children with LCH. The secreted OPN (sOPN) levels in CSF were measured through enzyme-linked immunosorbent assay (ELISA).

RESULTS

After the retrospective analysis of 57 patients with LCH, we found that the sOPN levels in CSF of children with posterior pituitary involvement were significantly higher than that of other groups. After the Pearson Chi-Square test, Fisher's exact test and ROC analysis, we found that the sOPN levels were significantly correlated with posterior pituitary involvement. The cut-off value is 214.14 ng/mL.

CONCLUSION

The sOPN levels were elevated in CSF of LCH children with posterior pituitary involvement. Analysis of the sOPN level may provide more accurate auxiliary diagnostic techniques for the clinic.

Pituitary sellar spine in a pediatric patient with diabetes insipidus

A sellar spine is a midline bony spur arising from the ventral aspect of the dorsum sellae. Representing a remnant of the anterior notochord, it is often an incidental finding and thought to be of no clinical significance. However, it has recently been suggested that a potential association may exist between sellar spine and pediatric pituitary endocrinopathies, possibly caused by deformation of the developing pituitary gland by the sellar spine. To our knowledge, this is the first case report demonstrating an association between sellar spine and clinical diabetes insipidus.

Altered cerebral perfusion in children with Langerhans cell histiocytosis after chemotherapy

BACKGROUND AND PURPOSE

Children with Langerhans cell histiocytosis (LCH) may develop a wide array of neurological symptoms, but associated cerebral physiologic changes are poorly understood. We examined cerebral hemodynamic properties of pediatric LCH using arterial spin-labeling (ASL) perfusion magnetic resonance imaging (MRI).

MATERIALS AND METHODS

A retrospective study was performed in 23 children with biopsy-proven LCH. Analysis was performed on routine brain MRI obtained before or after therapy. Region of interest (ROI) methodology was used to determine ASL cerebral blood flow (CBF) (mL/100 g/min) in the following bilateral regions: angular gyrus, anterior prefrontal cortex, orbitofrontal cortex, dorsal anterior cingulate cortex, and hippocampus. Quantile (median) regression was performed for each ROI location. CBF patterns were compared between pre- and posttreatment LCH patients as well as with age-matched healthy controls.

RESULTS

Significantly reduced CBF was seen in posttreatment children with LCH compared to age-matched controls in angular gyrus (P = .046), anterior prefrontal cortex (P = .039), and dorsal anterior cingulate cortex (P = .023). Further analysis revealed dominant perfusion abnormalities in the right hemisphere. No significant perfusion differences were observed in the hippocampus or orbitofrontal cortex.

CONCLUSION

Perfusion in specific cerebral regions may be consistently reduced in children with LCH, and may represent effects of underlying disease physiology and/or sequelae of chemotherapy. Studies that combine a formal cognitive assessment and hemodynamic data may further provide insight into perfusion deficits associated with the disease and the potential neurotoxic effects in children treated by chemotherapy.

Clinical Characteristics of Pediatric Patients With Sellar and Suprasellar Lesions Who Initially Present With Central Diabetes Insipidus: A Retrospective Study of 55 Cases From a Large Pituitary Center in China

Purpose: To increase knowledge for the early differential diagnosis and accurate therapeutic strategies for pediatric patients with sellar or suprasellar region (SSR) lesions who initially present with central diabetes insipidus (CDI). Methods: This is a retrospective review of 55 pediatric patients (≤14 years old) with identified lesions in the SSR who initially presented with CDI at a large pituitary center between 2012 and 2018. The following data were summarized: demographic, clinical, endocrine, and neuroimaging data, intraoperative findings, histopathological findings, treatments, and prognosis. Results: In our group, the etiologies of the SSR lesions included germ cell tumors (GCTs, 74.5%), Langerhans cell histiocytosis (LCH, 18.2%), and craniopharyngioma (CP, 7.3%). Almost all patients (50/55, 90.9%) showed anterior pituitary dysfunction [multiple axes dysfunction (38), and isolated axis dysfunction (14)], while the GH/IGF-I axis was the most affected. Most GCT patients presented with various clinical manifestations besides CDI and had elevated β-HCG, whereas LCH and CP patients mostly presented few non-specific symptoms besides CDI and most had normal level tumor markers. Sellar MRI demonstrated that posterior pituitary bright spot disappearance occurred in all patients, and pituitary stalk thickening was observed in 96.7% of patients. Treatment varied due to the different etiologies of the SSR lesions. After follow-up for 35.4 ± 20.2 months, the proportions of patients who needed AVP (arginine vasopressin) for GCT, LCH, and CP were 86.5, 100, and 75%, respectively, and the proportions of patients who needed HRT were 89.2, 50, and 75%, respectively. Conclusion: For pediatric SSR lesions that first manifest as CDI, we should comprehensively consider clinical characteristics and imaging features to aid in their early differential diagnosis. Tumor markers and surgical histopathology are also great complements for the differential diagnosis. Additionally, various treatment strategies should be adopted according to different causes to improve the child's prognosis and quality of life.

Isolated Langerhans cell histiocytosis in the hypothalamic-pituitary region: a case report

BACKGROUND

Langerhans cell histiocytosis (LCH) is a rare disease that mainly affects children, but this disease is significantly rarer in patients who are older than 15 years. In this disease, any organ can be involved. The skeleton, skin and lung are commonly affected, and isolated hypothalamic-pituitary (HP) involvement is relatively rare. Here we report a 17-year-old adolescent with isolated HP-LCH of enlarged pituitary stalk presented with central diabetes insipidus (CDI).

CASE PRESENTATION

A 17-year-old male adolescent with polydipsia and polyuria accompanied with elevated serum sodium level and low urine osmolality for 3 weeks was referred to our hospital. After admission, hormonal evaluation showed that his growth hormone (GH) was slightly elevated, and serum osmolality and glucose were normal. The fluid deprivation-vasopressin test demonstrated CDI. Imaging examination showed an obvious thickening of the pituitary stalk. Lymphocytic hypophysitis, sarcoidosis and granulation tissue lesions were suspected. After oral 1-deamino-8-Darginine vasopressin (DDAVP) and prednisone were administered for 2 months, symptoms were relieved, and he discontinued taking the drugs by himself. On reexamination, imaging revealed changes in the size and shape of the pituitary stalk, with thickened nodules. Then, a diagnostic biopsy of the pituitary stalk lesion was performed. Immunohistochemistry confirmed the definitive diagnosis of LCH. The clinical symptoms subsided with oral hormone replacements.

CONCLUSION

CDI is a rare symptom in children and adolescents. Most of the causes are idiopathic, while others are caused by central nervous system (CNS) disorders. Meanwhile, lymphocytic hypophysitis, germinoma, LCH and other CNS disorders can all present as thickening of the pituitary stalk, diffuse enlargement of the pituitary gland, and weakening of high signal intensity in the neurohypophysis on magnetic resonance imaging (MRI). The differential diagnosis among these diseases depends on immunohistochemistry evidence.

Neuroimaging features of CNS histiocytosis syndromes

Histiocytosis syndromes (HS) are group of heterogeneous disorders characterized by abnormal accumulation and infiltration of histiocytes, cells derived from hematopoietic cells of monocyte/macrophage lineage. Overall these disorders are rare. When they do occur they involve many organ systems including the central nervous system (CNS). While imaging findings can provide important clues, diagnosis of this disorder is challenging and definitive diagnosis often necessitates pathologic examination. In this review, we describe imaging features of HS involving the CNS, with the aim to increase our understanding of these disorders. The entities discussed in this review will include: Langerhans cell histiocytosis (LCH), Rosai-Dorfman Disease (RDD), Erdheim Chester Disease (ECD), hemophagocytic lymphohistiocytosis (HLH), and crystal-storing histiocytosis (CSH).

The Mayo Clinic Histiocytosis Working Group Consensus Statement for the Diagnosis and Evaluation of Adult Patients With Histiocytic Neoplasms: Erdheim-Chester Disease, Langerhans Cell Histiocytosis, and Rosai-Dorfman Disease

Histiocytic neoplasms, a rare and heterogeneous group of disorders, primarily include Erdheim-Chester disease, Langerhans cell histiocytosis, and Rosai-Dorfman disease. Due to their diverse clinical manifestations, the greatest challenge posed by these neoplasms is the establishment of a diagnosis, which often leads to a delay in institution of appropriate therapy. Recent insights into their genomic architecture demonstrating mitogen-activated protein kinase/extracellular signal-regulated kinase pathway mutations have now enabled potential treatment with targeted therapies in most patients. This consensus statement represents a joint document from a multidisciplinary group of physicians at Mayo Clinic who specialize in the management of adult histiocytic neoplasms. It consists of evidence- and consensus-based recommendations on when to suspect these neoplasms and what tests to order for the diagnosis and initial evaluation. In addition, it also describes the histopathologic and individual organ manifestations of these neoplasms to help the clinicians in identifying their key features. With uniform guidelines that aid in identifying these neoplasms, we hope to improve the awareness that may lead to their timely and correct diagnosis.

Rituximab therapy for patients with Langerhans cell histiocytosis-associated neurologic dysfunction

OBJECTIVE

Since patients with langerhans cell histiocytosis and neurologic dysfunction (LCH-ND) often have incomplete treatment responses we sought a new treatment regimen. Because of clinical benefit from rituximab in multiple sclerosis patients with neurodegeneration, we evaluated its use in patients with LCH-ND.

PARTICIPANTS

Eight LCH-ND patients who had failed prior therapies.

METHODS

Charts of the 8 patients treated with rituximab were reviewed. Signs/symptoms and MRI responses were assessed.

RESULTS

Seven of eight patients experienced some clinical improvement: gait abnormalities and tremors in four children, proprioceptive deficits in 2, and dysarthria/dysphagia in 2. Five of eight patients demonstrated improvement in intellectual/behavioral/psychological symptoms.

CONCLUSION

These findings suggest that prospective studies are warranted to define safety and efficacy of rituximab for patients with LCH-ND.