Biomarkers in the cerebrospinal fluid and neurodegeneration in Langerhans cell histiocytosis

[Central nervous system disorders secondary to histiocytoses: neurodegeneration with potential for improvement]

Histiocytoses, including Langerhans cell histiocytosis (LCH) and Erdheim-Chester disease (ECD), are inflammatory myeloid tumors in which monocyte lineage cells aggregate in various organs, causing tissue damage. Most of these tumors harbor oncogenic mutations in mitogen-activated protein kinase (MAPK) pathway genes, typified by BRAFV600E. Some patients with LCH develop bilateral symmetrical cerebellar lesions and brain atrophy several years after diagnosis when the initial symptoms disappear, leading to cerebellar ataxia and higher cerebral dysfunction. A similar neurological disorder has also been reported in ECD. This neurological disorder can be improved with MAPK inhibitors. When patients with this neurological disorder are identified among neurodegeneration of unknown etiology or histiocytosis patients and treated early with MAPK inhibitors, the disorder can be reversible.

Screening for neurodegeneration in Langerhans cell histiocytosis with neurofilament light in plasma

Patients with Langerhans cell histiocytosis (LCH) may develop progressive neurodegeneration in the central nervous system (ND‐CNS‐LCH). Neurofilament light protein (NFL) in cerebrospinal fluid (CSF) is a promising biomarker to detect and monitor ND‐CNS‐LCH. We compared paired samples of NFL in plasma (p‐NFL) and CSF in 10 patients (19 samples). Nine samples had abnormal CSF‐NFL (defined as ≥380 ng/l) with corresponding p‐NFL ≥ 2 ng/l. Ten samples had CSF‐NFL < 380 ng/l; eight (80%) with p‐NFL < 2 ng/l (p < 0.001; Fisher's exact test). Thus, our results suggest that p‐NFL may be used to screen for ND‐CNS‐LCH. Further studies are encouraged, including the role of p‐NFL for monitoring of ND‐CNS‐LCH.

A clinical approach to parasellar lesions in the transition age

Many reviews have summarised the pathology and management of the parasellar region in adult patients, although an analysis of these aspects in the transition years, from puberty onset to the age of peak bone mass, has been lacking. A comprehensive search of English-language original articles, published from 2000 to 2020, was conducted in the MEDLINE database (December 2019 to March 2020). We selected all studies regarding epidemiology, diagnosis and management of the following parasellar lesions: germinoma, craniopharyngioma, Langerhans cell histiocytosis, optic glioma, hypothalamic hamartoma, tuber cinereum hamartoma, cranial chordoma, Rathke cleft cyst, hypophysitis and hypothalamitis during the transition age from childhood to adulthood. In the present review, we provide an overview of the principal parasellar lesions occurring in the transition age. Symptoms are usually a result of the mass effect of the lesions on nearby structures, as well as anterior pituitary deficits. Diabetes insipidus occurs frequently in these patients. In this age group, pubertal developmental disorders may be more evident compared to other stages of life. Parasellar lesions in the transition age mostly include neoplastic lesions such as germinomas, hamartomas, optic gliomas, craniopharyngiomas Langerhans cell histiocytosis and chordomas, and rarely inflammatory lesions (hypophysitis, hypothalamitis). There are limited data on the management of parasellar lesions in the transition age. Endocrine evaluation is crucial for identifying conditions that require hormonal treatment so that they can be treated early to improve the quality of life of the individual patient in this complex age range. The clinical approach to parasellar lesions involves a multidisciplinary effort.

Pituitary Stalk Enlargement in Adults

Pathologies involving the pituitary stalk (PS) are generally revealed by the presence of diabetes insipidus. The availability of MRI provides a major diagnostic contribution by enabling the visualization of the site of the culprit lesion, especially when it is small. However, when only an enlarged PS is found, the etiological workup may be difficult, particularly because the biopsy of the stalk is difficult, harmful and often not contributive. The pathological proof of the etiology thus needs to be obtained indirectly. The aim of this article was to provide an accurate review of the literature about PS enlargement in adults describing the differences between the numerous etiologies involved and consequent different diagnostic approaches. The etiological diagnostic procedure begins with the search for possible other lesions suggestive of histiocytosis, sarcoidosis, tuberculosis or other etiologies elsewhere in the body that could be more easily biopsied. We usually perform neck, thorax, abdomen, and pelvis CT scan; positron emission tomography scan; bone scan; or other imaging methods when we suspect generalized lesions. Measurement of serum markers such as human chorionic gonadotropin, alpha-fetoprotein, angiotensin converting enzyme, and IgG4 may also be helpful. Obviously, in the presence of an underlying carcinoma (particularly breast or bronchopulmonary), one must first consider a metastasis located in the PS. In the case of an isolated PS enlargement, simple monitoring, without histological proof, can be proposed (by repeating MRI at 3-6 months) with the hypothesis of a germinoma (particularly in a teenager or a young adult) that, by increasing in size, necessitates a biopsy. In contrast, a spontaneous diminution of the lesion is suggestive of infundibulo-neurohypophysitis. We prefer not to initiate steroid therapy to monitor the spontaneous course when a watch-and-see attitude is preferred. However, in many cases, the etiological diagnosis remains uncertain, requiring either close monitoring of the lesion or, in exceptional situations, trying to obtain definitive pathological evidence by a biopsy, which, unfortunately, is in most cases performed by the transcranial route. If a simple surveillance is chosen, it has to be very prolonged (annual surveillance). Indeed, progression of histiocytosis or germinoma may be delayed.

CNS Langerhans cell histiocytosis: Common hematopoietic origin for LCH-associated neurodegeneration and mass lesions

BACKGROUND

Central nervous system Langerhans cell histiocytosis (CNS-LCH) brain involvement may include mass lesions and/or a neurodegenerative disease (LCH-ND) of unknown etiology. The goal of this study was to define the mechanisms of pathogenesis that drive CNS-LCH.

METHODS

Cerebrospinal fluid (CSF) biomarkers including CSF proteins and extracellular BRAFV600E DNA were analyzed in CSF from patients with CNS-LCH lesions compared with patients with brain tumors and other neurodegenerative conditions. Additionally, the presence of BRAFV600E was tested in peripheral mononuclear blood cells (PBMCs) as well as brain biopsies from LCH-ND patients, and the response to BRAF-V600E inhibitor was evaluated in 4 patients with progressive disease.

RESULTS

Osteopontin was the only consistently elevated CSF protein in patients with CNS-LCH compared with patients with other brain pathologies. BRAFV600E DNA was detected in CSF of only 2/20 (10%) cases, both with LCH-ND and active lesions outside the CNS. However, BRAFV600E+ PBMCs were detected with significantly higher frequency at all stages of therapy in LCH patients who developed LCH-ND. Brain biopsies of patients with LCH-ND demonstrated diffuse perivascular infiltration by BRAFV600E+ cells with monocyte phenotype (CD14+ CD33+ CD163+ P2RY12- ) and associated osteopontin expression. Three of 4 patients with LCH-ND treated with BRAF-V600E inhibitor experienced significant clinical and radiologic improvement.

CONCLUSION

In LCH-ND patients, BRAFV600E+ cells in PBMCs and infiltrating myeloid/monocytic cells in the brain is consistent with LCH-ND as an active demyelinating process arising from a mutated hematopoietic precursor from which LCH lesion CD207+ cells are also derived. Therapy directed against myeloid precursors with activated MAPK signaling may be effective for LCH-ND. Cancer 2018;124:2607-20. © 2018 American Cancer Society.

Pituitary stalk thickening on MRI: when is the best time to re-scan and how long should we continue re-scanning for?

Magnetic resonance imaging (MRI) has proved to be an essential tool in the assessment of pituitary stalk lesions including lymphocytic infundibulo-hypophysitis, Langerhans cell histiocytosis (LCH), germ cell tumours, nongerminomatous germ cell tumours, pituicytomas and other tumours, metastases from lymphoma or breast cancer, Wegener's hypophysitis, neurosarcoidosis and inflammatory infiltrations by infectious diseases. The diagnosis of lesions determining pituitary stalk thickness is challenging, and the identification of the underlying condition may require a long-term follow-up. Thus, clinicians should readily recognize that, when the diagnosis of central diabetes insipidus has been established, specific MRI sequences should be used in the assessment of the hypothalamic-pituitary region, and whole-brain evaluation is recommended. For clinical practice, a timely diagnosis is advisable to avoid central nervous system damage, pituitary defects and the risk of dissemination of germ cell tumours or organ involvement by LCH. Proper aetiological diagnosis can be achieved via a series of steps that start with careful observation of several neuroimaging predictors and endocrine dysfunction and then progress to more sophisticated and advanced imaging techniques.

Langerhans cell histiocytosis in an adult with involvement of the calvarium, cerebral cortex and brainstem: discussion of pathophysiology and rationale for the use of intravenous immune globulin

We report a case of Langerhans cell histiocytosis in a 64-year-old male who presented with symptoms and signs of brain involvement, including seizures and hypopituitarism. The diagnosis was confirmed with a biopsy of a lytic skull lesion. The disease affecting the bone showed no sign of progression following a short course of cladribine. Signs of temporal lobe involvement led to an additional biopsy, which showed signs of nonspecific neurodegeneration and which triggered status epilepticus. Lesions noted in the brainstem were typical for the paraneoplastic inflammation reported in this condition. These lesions improved after treatment with cladribine. They remained stable while on treatment with intravenous immune globulin.

Prognostic value of brain injury biomarkers in acute encephalitis/encephalopathy

BACKGROUND

Acute encephalitis/encephalopathy (AEE) is a devastating cause of severe neurodevelopmental sequelae or death in children. Assessing ongoing brain injury and predicting outcomes using bedside point-of-care testing is expected to be extremely valuable.

METHODS

For this study, three brain injury markers, S-100B, glial fibrillary acidic protein (GFAP), and tau protein, were measured in early cerebrospinal fluid samples of children with AEE. Subjects comprised three groups: Group 1 (non-AEE control, n = 27); Group 2 (AEE with normal resolution or mild sequelae, n = 13); and Group 3 (AEE with severe sequelae or death, i.e. "poor outcome," n = 10).

RESULTS

All marker levels were significantly higher in Group 3 than in Group 1 or 2. In Group 3, only S-100B was significantly higher in non-survivors than in survivors. For scoring assessment (range: 0-3 points), the predictive accuracies of 3 points for poor outcomes in children with AEE (i.e. Group 2 and 3, n = 23) were 91% (21/23) for S-100B, 74% (17/23) for GFAP, and 78% (18/23) for tau. When the scores were summed up for S-100B, GFAP, and tau (range: 0-9 points), and for S-100B and tau (range: 0-6 points), the patients with poor outcomes were identified more accurately using the respective thresholds of 6 points and 4 points (96% [22/23] and 100% [23/23], respectively).

CONCLUSION

Our findings suggest that combined measurement and scoring assessment of the markers, especially S-100B and tau, show promise as predictors of clinical outcomes in children with AEE.

Cerebrospinal fluid brain injury biomarkers in children: a multicenter study

BACKGROUND

Cerebrospinal fluid (CSF) biomarkers reflecting neuronal and astroglial injury, such as total tau (T-tau), glial fibrillary acidic protein (GFAP), and neurofilament light (NFL), have been extensively investigated in neurologic diseases in adults, but no large study has investigated these biomarkers in children.

METHODS

This study presents a detailed evaluation of CFS T-tau, GFAP, NFL, and CSF:albumin ratio in a large cohort of pediatric patients. This is a retrospective multicenter study on pediatric patients aged <16 years (n = 607), where neuronal injury biomarkers T-tau, GFAP, NFL, and CSF albumin ratio were analyzed during 2000-2010 at the Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Sweden. The patients were grouped into eight categories: epilepsy, infectious and inflammatory central nervous system disorders, progressive encephalopathy, static encephalopathy, tumors, movement disorders, miscellaneous disorders, and a control group.

RESULTS

T-tau, GFAP, and NFL were increased in progressive encephalopathy (P < 0.001), epilepsy (P < 0.001), and infectious and inflammatory central nervous system disorders (P < 0.001) compared with controls. T-tau was the biomarker with the highest diagnostic accuracy with the area under the curve of 0.83 (95% confidence interval (CI), 0.77-0.90; P < 0.0001) for progressive encephalopathy followed by epilepsy 0.80 (95% CI, 0.75-0.87; P < 0.0001). The combination of all four biomarkers further improved the area under the curve for the progressive encephalopathy 0.87 (95% CI, 0.77-0.89; P < 0.0001), followed by epilepsy 0.81 (95% CI, 0.74-0.80; P = 0.030). The combination of the biomarkers also separated progressive from static encephalopathy 0.88 (95% CI, 0.83-0.93; P < 0.0001).

CONCLUSIONS

CSF T-tau, GFAP, and NFL are differently altered across different neurologic diseases in children. Importantly, the biomarker pattern distinguishes between progressive and static neurologic disorders.

Cerebrospinal fluid biomarkers in neurological diseases in children

Analysis of cerebrospinal fluid (CSF) biomarkers is an integral part of neurology. Basic CSF biomarkers, such as CSF/serum albumin ratio and CSF cell counts, have been used to diagnose inflammatory and infectious CNS disorders in adults and children for decades. During recent years, however, numerous biomarkers for neuronal and astroglial injury, as well as disease-specific protein inclusions, have been developed for neurodegenerative disorders in adults. The overall aim of this paper is to give an updated overview of some of these biomarkers with special focus on their possible relevance to neurological disorders in children and adolescents.

Neither IL-17A mRNA nor IL-17A protein are detectable in Langerhans cell histiocytosis lesions

Langerhans cell histiocytosis (LCH) is a rare disease characterized by heterogeneous lesions including CD207(+)/CD1a(+) dendritic cells that can result in significant morbidity and mortality. The etiology of LCH remains speculative, and neoplastic and inflammatory origins have been debated for decades. A recent study identified abundant interleukin-17 (IL-17A) protein in dendritic cells in LCH lesions as well as in plasma from patients with active disease. Furthermore, it identified dendritic cells as a novel source of IL-17A expression. However, subsequent studies from our research group failed to identify any IL-17A gene expression from CD207(+) dendritic cells or CD3(+) T cells in LCH lesions. In this study, further investigation once again fails to identify any cells in LCH lesions with IL-17A gene expression. Furthermore, IL-17A antigen is undetectable in LCH lesion lysates with western blotting, immunoprecipitation, spectral analysis, and enzyme-linked immunosorbent assay (ELISA). Western blots, immunoprecipitation, and ELISA experiments also demonstrate that antibodies used in original studies that established the IL-17A hypothesis for pathogenesis of LCH recognize nonspecific proteins. We conclude that evidence for IL-17A as a significant factor in LCH remains inadequate and clinical trials targeting IL-17A remain unjustified.

Incidence and pattern of radiological central nervous system Langerhans cell histiocytosis in children: a population based study

BACKGROUND

Patients with Langerhans cell histiocytosis (LCH) may develop neurodegeneration and other central nervous system (CNS) dysfunctions revealed by brain magnetic resonance imaging (MRI). We estimated the incidence and pattern of pathological brain MRI findings in a well-defined, population-based cohort of children with LCH.

METHODS

Among children under 15 years of age diagnosed with LCH in the Stockholm County during 1992-2001, brain MRI was performed at a single center in children with clinical and/or laboratory signs of CNS involvement, including endocrine dysfunction.

RESULTS

Out of the 29 children (16 males, 13 females) diagnosed with LCH, brain MRI was performed based on clinical indications in 16 children (55%) with either abnormal endocrine findings (n = 6), such as diabetes insipidus (n = 5), low IGF-1 (n = 1), or panhypopituitarism (n = 1), or clinical CNS symptoms (n = 10). CNS MRI abnormalities were demonstrated in eight children (28%), at a median time of 3.5 years after LCH diagnosis (range 1-11.4 years). Altogether 7 of the 29 children (24%) had MRI findings associated with neurodegeneration, corresponding to a minimal incidence of 2.1/10(6) children per year. Neurodegenerative abnormalities tended to be more frequent in patients with craniofacial involvement (P = 0.12).

CONCLUSIONS

The minimal annual incidence rate of neurodegenerative associated radiographic findings in LCH is estimated at 2.1/10(6) children (24% of all children with LCH). An important question is whether all patients with LCH, or certain forms of LCH, should be recommended for a late follow-up examination including MRI. In patients with CNS-LCH, neurological, neuropsychological, neurophysiological, neurochemical and neuroradiological follow-up assessment is suggested.