Neuroradiologic manifestations of Erdheim-Chester disease

Central nervous system involvement in Erdheim-Chester disease: a magnetic resonance imaging study

PURPOSE

To characterize brain MR imaging findings in a cohort of 58 patients with ECD and to evaluate relationship between these findings and the BRAFV600E pathogenic variant.

METHODS

ECD patients of any gender and ethnicity, aged 2-80 years, with biopsy-confirmed ECD were eligible to enroll in this study. Two radiologists experienced in evaluating ECD CNS disease activity reviewed MRI studies. Any disagreements were resolved by a third reader. Frequencies of observed lesions were reported. The association between the distribution of CNS lesions and the BRAFV600Epathogenic variant was evaluated using Fisher's exact test and odd ratio.

RESULTS

The brain MRI of all 58 patients with ECD revealed some form of CNS lesions, most likely due to ECD. Cortical lesions were noted in 27/58 (46.6 %) patients, cerebellar lesions in 15/58 (25.9 %) patients, brain stem lesions in 17/58 cases (29.3 %), and pituitary lesions in 10/58 (17.2 %) patients. Premature cortical atrophy was observed in 8/58 (13.8 %) patients. BRAFV600E pathogenic variant was significantly associated with cerebellar lesions (p = 0.016) and bilateral brain stem lesions (p = 0.043). A trend toward significance was noted for cerebral atrophy (p = 0.053).

CONCLUSION

The study provides valuable insights into the brain MRI findings in ECD and their association with the BRAFV600E pathogenic variant, particularly its association in cases with bilateral lesions. We are expanding our understanding of how ECD affects cerebral structures. Knowledge of MRI CNS lesion patterns and their association with mutations such as the BRAF variant is helpful for both prognosis and clinical management.

Cerebral Tumefactive Inflammatory Lesion Occurrence During Ixekizumab Treatment in a Patient With Active Psoriatic Arthritis

INTRODUCTION

Ixekizumab is an anti-interleukin-17A (IL-17A) humanized monoclonal antibody approved for the treatment of moderate-to-severe plaque psoriasis, active psoriatic arthritis, and ankylosing spondylitis. Central nervous system inflammatory manifestations are atypical during therapy with IL-17A inhibitors, with only one case of myelitis described to date.

CASE REPORT

A 72-year-old man with a medical history of active psoriatic arthritis was admitted to our department owing to the acute onset of left face numbness 1 month after the first ixekizumab administration. Magnetic resonance imaging of the brain displayed a large T2-hyperintense infratentorial lesion involving the root of the fifth and seventh left cranial nerves. A thorough laboratoristic and instrumental work-up did not show elements suggestive of extracerebral neoplasms or infections. Therefore, neuronavigation-assisted brain biopsy was performed, and histologic analysis of the lesion revealed the presence of wide aggregates of foamy histiocytes diffusely infiltrating the brain parenchyma, in the absence of malignant tissue or histologic elements suggestive of central nervous system infections or primary histiocytoses. Steroid treatment (dexamethasone 8 mg/daily) was then administered with subsequent clinical amelioration. One month after hospital discharge, a brain magnetic resonance imaging showed a nearly complete resolution of the lesion.

CONCLUSION

This is the first case of a cerebral inflammatory lesion occurring during treatment with ixekizumab. Although very rare, neurological complications may occur during anti-IL-17A therapies, thus leading to the need for careful monitoring of patients exposed to these drugs.

Erdheim-Chester disease of brain parenchyma without any systemic involvement: A case report and review of literature

Erdheim-Chester disease is a non-Langerhans cell histiocytosis syndrome characterised by histiocytic infiltration of different organs and systems in the body. Erdheim-Chester disease with isolated central nervous system (CNS) involvement causes diagnostic difficulties due to the absence of systemic findings and may result in misdiagnosis and inaccurate treatment choices. The case discussed in this report exemplifies how challenging it is to diagnose Erdheim-Chester disease with isolated CNS involvement. This case, which presented with progressive pyramidocerebellar syndrome, was clinically and radiologically resistant to all immunosuppressive and immunomodulatory treatments administered. The presence of false negative results in repeated histopathological investigations and the absence of evidence for systemic disease hindered the diagnosis and treatment work-up. In this study, we reviewed and discussed the prominent features of the presented case in light of the relevant literature.

Dabrafenib and steroids for the treatment of Erdheim-Chester disease with extensive CNS involvement: a case report

Erdheim-Chester disease (ECD) is an exceedingly rare non-Langerhans cell CD68+ CD1a- S100- histiocytic multi-organ disease. Diagnosis of ECD is often delayed due to non-specific radiographic findings and heterogeneous lesional tissue. Increasingly, the role of genomic alterations is being recognized for both diagnosis and treatment of ECD. More than half of ECD patients harbor the BRAFV600E mutation. Evaluation for this mutation be can falsely negative on immunohistochemical staining and confirmation with molecular analyses is recommended. We present a case of the 44 year-old male with BRAFV600E-positive ECD treated successfully with steroids followed by single-agent dabrafenib.

Neuroimaging manifestations of paediatric histiocytoses

Histiocytoses are rare multi-system disorders marked by abnormal histiocyte cell proliferation, affecting children with diverse clinical presentations. Classified into five groups in 2016, including Langerhans-related (L), cutaneous (C), malignant (M), Rosai-Dorfman disease (R) and haemophagocytic lymphohistiocytosis (H), newer entities such as ALK-positive histiocytosis have also emerged, heralding the era of molecular (sub)classification. Common entities include Langerhans cell histiocytosis (LCH), Erdheim-Chester disease (ECD), Rosai-Dorfman disease (RDD) and haemophagocytic lymphohistiocytosis (HLH). This pictorial essay aids radiologists in recognising and differentiating paediatric histiocytoses based on unique neuroimaging features.

Recurrent petit mal seizures in Erdheim-Chester disease mimicking an intra-axial brain tumor: illustrative case

BACKGROUND

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis characterized histologically by foamy histiocytes and Touton giant cells in a background of fibrosis. Bone pain with long bone osteosclerosis is highly specific for ECD. Central nervous system involvement is rare, although dural, hypothalamic, cerebellar, brainstem, and sellar region involvement has been described.

OBSERVATIONS

A 59-year-old man with a history of ureteral obstruction, medically managed petit mal seizures, and a left temporal lesion followed with serial magnetic resonance imaging (MRI) presented with worsening seizure control. Repeat MRI identified bilateral amygdala region lesions. Gradual growth of the left temporal lesion over 1 year with increasing seizure frequency prompted resection. A non-Langerhans cell histiocytosis with a BRAF V600E mutation was identified on pathology. Imaging findings demonstrated retroperitoneal fibrosis and long bone osteosclerosis with increased fluorodeoxyglucose uptake that, together with the neuropathologic findings, were diagnostic of ECD.

LESSONS

This case of biopsy-proven ECD is unique in that the singular symptom was seizures well controlled with medical management in the presence of similarly located bilateral anterior mesial temporal lobe lesions. Although ECD is rare intracranially, its variable imaging presentation, including the potential to mimic seizure-associated medial temporal lobe tumors, emphasizes the need for a wide differential diagnosis.

Novel paraneoplastic mechanism for cerebellar ataxia in Erdheim-Chester disease

We report a case of BRAF-mutation positive Erdheim-Chester disease presenting with a cerebellar ataxia. This is the first such case to be reported without structural MRI abnormalities but with a single intrathecally produced oligoclonal band. Now that the histiocytoses have been recharacterised as neoplastic, we speculate that the mechanism of the ataxia in our case is paraneoplastic. We highlight the importance of searching for BRAF mutations in this disease, as their presence leads to effective personalised treatments.

Presyncope and Ophthalmoparesis Due to Intracranial Erdheim-Chester Disease

Introduction

An 82-year-old female presented to the emergency department with presyncope and was found to be bradycardic with proptosis and ophthalmoparesis. MRI revealed an extra-axial enhancing mass compressing the medulla and bilateral enhancing retro-orbital masses.

Case Description

Imaging, including nuclear medicine bone scan, PET CT, and cardiac MRI raised the suspicion for a histiocytic neoplasm. These findings, along with a fibrohistiocytic infiltrate on bone biopsy and a BRAF V600E oncogenic mutation on plasma cell-free DNA confirmed a diagnosis of Erdheim-Chester disease.

Discussion

These enhancing masses invoke a broad differential, including a histiocytic or granulomatous process, fungal infection, amyloidosis, IgG4 disease, and lymphoma. Systematic laboratory, radiologic, pathology, and genetic testing yielded a diagnosis of this rare histiocytic disorder with frequent neurologic involvement.

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.

Pancreatic involvement in Erdheim-Chester disease: Rare presentation of a rare disease

Erdheim-Chester disease (ECD) as a rare non-Langerhans histiocytosis has various clinical manifestations. It is characterized histologically by infiltration of every organ, more commonly bone, retroperitoneum, cardiovascular and CNS systems with foamy, lipid -laden macrophage. Pancreatic involvement as a manifestation of this uncommon disease has very rarely been reported. Here we report a 73-year-old woman with ECD and pancreas involvement in CT, MRI and PET scans. We also aim to increase radiologist knowledge about considering ECD as a differential diagnosis for pancreas mass in the appropriate clinical situation.

Ophthalmologic Involvement in Adults with Histiocytic Disorders: Clinical Presentation and Treatment Outcomes

PURPOSE

To evaluate the clinical presentation, treatment, and outcomes in adult patients with histiocytic disorders with ocular, orbital, optic nerve, or cavernous sinus involvement.

DESIGN

Observational, retrospective chart review.

PARTICIPANTS

Adult patients (age ≥ 18 years) at Mayo Clinic from January 1, 1996, to July 1, 2021, with histiocytic disorders. Inclusion criteria were (1) histiocytic disorder by biopsy and appropriate clinical phenotype; (2) available medical records; and (3) ocular, orbital, optic nerve, or cavernous sinus involvement.

METHODS

Retrospective chart review.

MAIN OUTCOME MEASURES

Response to therapy, measured in clinical and radiographic impact.

RESULTS

Thirty-two patients were identified: 7 with Langerhans cell histiocytosis (LCH); 15 with Erdheim-Chester disease (ECD); 1 with mixed LCH/ECD phenotype; 8 with Rosai-Dorfman disease (RDD); and 1 with mixed RDD/ECD phenotype. Ophthalmologic involvement was part of the initial presentation in 69% of patients (22/32). Eyelid edema (13/32, 41%) and proptosis (12/32, 38%) were the most frequent presentations. Isolated orbital or cavernous sinus involvement was present in 3 of 7 patients with LCH and 1 of 8 patients with RDD. Optic nerve sheath involvement was present in 2 of 7 LCH patients, 14 of 15 ECD patients, and 1 RDD/ECD patient. Diffuse (> 75%) orbital involvement was seen in 12 of 15 ECD patients and 1 of 7 LCH patients. Ocular involvement was seen in 1 of 15 ECD patients, 6 of 8 RDD patients, and 1 of 1 mixed RDD/ECD patient. The cavernous sinuses were involved in 1 of 7 LCH patients, 5 of 15 ECD patients, and both mixed phenotype patients. Visual acuity was affected in 14 patients (14/24, 58%) with a median logarithm of the minimum angle of resolution visual acuity of 0.1 (range, -0.12 to 3). BRAF V600E mutations were found in 75% (3/4) of LCH patients and 91% (10/11) of ECD patients. Patients received a variety of treatment, and response was variable across disease types.

CONCLUSIONS

Orbital involvement was more commonly seen in LCH and ECD, whereas ocular involvement was more common in RDD. Visual acuity may be impacted from ocular involvement or compression of the optic nerve with diffuse orbital involvement.

Erdheim-Chester disease: Typical radiologic findings of a multisystemic disease

Erdheim-Chester disease is a rare and multisystemic entity. It results from the infiltration of tissues by foamy histiocytes. The etiology is unknown, but there are mutations in the MAPK pathway in over 80% of patients, more frequently BRAF mutation. The most commonly affected organs and systems are the skeleton, central nervous system, cardiovascular system, kidney, lungs, and skin. The most common clinical manifestations are bone pain, usually in the lower limbs, and diabetes insipidus. The diagnosis is challenging. It requires a combination of clinical, radiological, histopathological, and molecular findings. We present the case of a patient with typical clinical and radiological manifestations: bone pain and diabetes insipidus at presentation, bilateral long bone cortical sclerosis, hairy kidney appearance, coated aorta, right atrium pseudotumor, and periorbital masses.

Erdheim-Chester Disease Involving the Central Nervous System with Latent Toxoplasmosis

Erdheim-Chester disease (ECD) is a rare, non-Langerhans cell histiocytosis characterized by the infiltration of foamy histiocytes into multiple organs. We herein report a case of ECD with central nervous system (CNS) involvement in a 63-year-old man who also presented a positive result for Toxoplasma gondii nested polymerase chain reaction testing of cerebrospinal fluid. Since anti-Toxoplasma treatment proved completely ineffective, we presumed latent infection of the CNS with T. gondii. This case suggests the difficulty of distinguishing ECD with CNS involvement from toxoplasmic encephalitis and the possibility of a relationship between the pathogeneses of ECD and infection with T. gondii.

Craniospinal irradiation for respiratory failure secondary to central nervous system Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis typically featuring lower extremity osteosclerosis (96%) from Langerin-negative histiocytes with fibrosis. Central nervous system (CNS)-only disease is extremely rare, and particularly difficult to diagnose and manage. Neurologic complaints may be refractory to systemic therapy (ST), and the role of radiation therapy (RT) is undefined. We present a patient with ECD of the medulla complicated by respiratory failure and strength deficits with disseminated leptomeningeal disease (LMD) but not systemic disease, representing the first report of CNS-limited ECD with LMD. He received upfront craniospinal irradiation (CSI), representing a rare account of CSI for ESD, with marked clinical improvement resulting in extubation and improved strength. CSI facilitated excellent preservation of quality of life, and no treatment-related toxicity was observed prior to eventual, unrelated cardiopulmonary arrest. Thus, palliative CSI may augment ST by safely offering improved local control and symptomatic relief for CNS ECD.

Erdheim-Chester Disease Revealed by Central Positional Nystagmus: A Case Report

Erdheim-Chester disease (ECD) is a rare histiocytic disorder, recently recognized to be neoplastic. The clinical phenotype of the disease is extremely heterogeneous, and depends on the affected organs, with the most frequently reported manifestations being bone pain, diabetes insipidus and neurological disorders including ataxia. In this article, we report on a case of a 48-year-old woman, whose initial symptom of gait instability was isolated. This was associated with positional nystagmus with central features: nystagmus occurring without latency, clinically present with only mild symptoms, and resistant to repositioning maneuvers. The cerebral MRI showed bilateral intra-orbital retro-ocular mass lesions surrounding the optic nerves and T2 hyperintensities in the pons and middle cerebellar peduncles. A subsequent CT scan of the chest abdomen and pelvis found a left “hairy kidney”, while ¹⁸ F-FDG PET-CT imaging disclosed symmetric 18F-FDG avidity predominant at the diametaphyseal half of both femurs. Percutaneous US-guided biopsy of perinephric infiltrates and the kidney showed infiltration by CD68(+), CD1a(-), Langerin(-), PS100(-) foamy histiocytes with BRAF^V600E mutation. The combination of the different radiological abnormalities and the result of the biopsy confirmed the diagnosis of ECD. Many clinical and radiological descriptions are available in the literature, but few authors describe vestibulo-ocular abnormalities in patients with ECD. Here, we report on a case of ECD and provide a precise description of the instability related to central positional nystagmus, which led to the diagnosis of ECD.

Endoscopic Transsphenoidal Resection of Suprasellar Histiocytosis in a Patient with Erdheim-Chester Disease: A Case Report

Erdheim–Chester disease (ECD) is a rare systemic disease characterized by non-Langerhans histiocytosis. Pituitary involvement, often manifesting as diabetes insipidus, is the most common central nervous system (CNS) lesion. However, significant mass formation compressing the optic apparatus is rarely reported. We present a case of ECD-related suprasellar mass treated with an endoscopic transnasal approach, with emphasis on the surgical strategy and the intraoperative findings. The mass was fibrous, significantly hard, and strongly adhered to the optic nerves, causing visual impairment. A subtotal resection was performed with preserving the adhesion between the mass and the optic nerves, and her visual symptoms improved remarkably after surgery. We highlight the surgical procedure of ECD-related suprasellar mass, from an endoscopic point of view. Due to strong adhesion of the mass to the surrounding optic apparatus and perforators, complete resection may be harmful; judicious mass reduction with preserving such adhesion would contribute to better visual outcomes.

Solitary Radiolucent Erdheim-chester Disease: A Case Report and Literature Review

Background:

Erdheim-chester disease (ECD) is a rare non-Langerhans histiocytosis of unknown etiology, which typically presents with bilateral symmetric osteosclerosis and multi-organ involvement. Lesions may be intraosseous or extraosseous and involve the heart, pulmonary system, CNS, and skin in order of decreasing likelihood.

Objective:

The objective of this study is to discuss a case of erdheim-chester disease and conduct a review of the literature.

Case:

We describe a rare case of erdheim-chester in an asymptomatic 37-year-old male who was diagnosed after suffering a right ulnar injury. Subsequent evaluation revealed a solitary radiolucent ulnar lesion without multi-system involvement.

Results & Conclusion:

The case is unique in its solitary distribution, lytic radiographic appearance, and asymptomatic presentation preceding pathologic fracture. This presentation may simulate multiple other bone lesions.

Clinical approach to neuro-rheumatology

Recognizing the neurologic manifestations of systemic rheumatologic diseases and certain isolated autoimmune neurologic diseases poses challenges to the clinician. Using a systematic approach allows the clinician to diagnose these conditions more readily and to initiate treatment more rapidly. Specific neurological syndromes frequently associated with rheumatologic or specific autoimmune conditions can suggest the diagnosis. A targeted history and examination can identify neurological and systemic clues that help to identify an underlying rheumatologic condition. Judicious use of laboratory and radiographic studies can help confirm suspected diagnoses. This article will review some of the neurological syndromes typical of rheumatologic disease and outline an approach to evaluating for unknown rheumatologic disease in this context.

Erdheim–Chester disease: with neurological manifestation and multisystem involvement: case report and radiological review

Background

Erdheim–Chester disease (ECD) is a rarely encountered idiopathic systemic form of non-Langerhans cell histiocytosis. The clinical manifestations of ECD are highly heterogeneous, ranging from unifocal forms to life-threatening multisystem involvement. Patients with CNS involvement often do not show clinical remission.

Case presentation

We present a case of a 60-year-old male patient with worsening complaints of loss of balance, involuntary jerky movements, emotional lability and scanning speech developing over a period of 5 years. Magnetic resonance imaging of the brain at present institute revealed signal abnormalities in the midbrain, pons, cerebellar peduncles and cerebellar white matter with mineral deposition and volume loss in the bilateral basal ganglia and midbrain. Positron emission tomography–computed tomography of chest and abdomen revealed 18-fluorodeoxyglucose avid soft tissues lesion in the retroperitoneum involving bilateral perinephric spaces with intra-renal sinus extension, in pre- and paraaortic regions with enlargement of both adrenal glands. The radiographs of the long bones revealed multiple areas of sclerosis. The suspected diagnosis of ECD was confirmed on histopathology. ECD is a rare disease and has a predilection towards middle-aged males and is usually diagnosed late after the onset of initial symptoms.

Conclusions

Our case was an atypical presentation of an extremely rare disease, presenting with ataxia and choreoathetoid movements linked to ferromagnetic deposition on brain scans. Multiple other imaging feature characteristics of the disease like the hairy kidney sign, coated aorta sign, skeletal, extra-skeletal and central nervous system manifestations were noted in this single patient.

Histiocytic Neoplasms, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

Histiocytic neoplasms are rare hematologic disorders accounting for less than 1% of cancers of the soft tissue and lymph nodes. Clinical presentation and prognosis of these disorders can be highly variable, leading to challenges for diagnosis and optimal management of these patients. Treatment often consists of systemic therapy, and recent studies support use of targeted therapies for patients with these disorders. Observation ("watch and wait") may be sufficient for select patients with mild disease. These NCCN Guidelines for Histiocytic Neoplasms include recommendations for diagnosis and treatment of adults with the most common histiocytic disorders: Langerhans cell histiocytosis, Erdheim-Chester disease, and Rosai-Dorfman disease.

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.

A case of multiple cranial nerve palsies

Multiple cranial nerve palsies have many possible causes, including infective, inflammatory, neoplastic and infiltrative diseases of the meninges or skull base. We present the clinicopathological conference of a 27-year-old man with a smouldering course of sequential cranial nerve palsies. His imaging showed dural thickening and osteosclerosis of the skull base with otomastoiditis. Cerebrospinal fluid showed lymphocytic pleocytosis with reduced glucose and normal protein concentrations. There was a possible response to corticosteroids and anti-tubercular treatment. Initial biopsy from the thickened and enhancing dura was unremarkable. His condition deteriorated after the steroids were tapered; MR imaging showed progression of lesions and positron emission tomography showed intense hypermetabolism. Subsequently, a diagnostic test revealed the final diagnosis. This case was presented at the All India Institute of Medical Sciences’ monthly clinicopathological conference series in February 2021.

Erdheim-Chester Disease With Concurrent Lung Adenocarcinoma

Erdheim-Chester disease (ECD) is a rare type of blood cancer characterized by infiltration of the body tissues by pathologic histiocytes, leading to widespread inflammation and damage. Clinical presentations range widely, from asymptomatic infiltration of bone to multiple organ system damage and resultant dysfunction. This report describes a case of a patient with several unusual imaging findings that led to a differential diagnosis of ECD; however, a biopsy of a mediastinal mass suspected to be due to histiocyte infiltration instead revealed primary lung cancer. Ultimately, ECD could not be ruled out, and the patient was referred to dermatology for a superficial facial xanthelasma biopsy, results of which were consistent with ECD. Concurrent ECD and adenocarcinoma is highly unusual; this case demonstrates the importance of a thorough investigation and the consideration that not all findings may be attributable to a single disease process, even when the alternative is very unlikely.

Erdheim-Chester disease: consensus recommendations for evaluation, diagnosis, and treatment in the molecular era

Erdheim-Chester disease (ECD) is a rare histiocytosis that was recently recognized as a neoplastic disorder owing to the discovery of recurrent activating MAPK (RAS-RAF-MEK-ERK) pathway mutations. Typical findings of ECD include central diabetes insipidus, restrictive pericarditis, perinephric fibrosis, and sclerotic bone lesions. The histopathologic diagnosis of ECD is often challenging due to nonspecific inflammatory and fibrotic findings on histopathologic review of tissue specimens. Additionally, the association of ECD with unusual tissue tropism and an insidious onset often results in diagnostic errors and delays. Most patients with ECD require treatment, except for a minority of patients with minimally symptomatic single-organ disease. The first ECD consensus guidelines were published in 2014 on behalf of the physicians and researchers within the Erdheim-Chester Disease Global Alliance. With the recent molecular discoveries and the approval of the first targeted therapy (vemurafenib) for BRAF-V600-mutant ECD, there is a need for updated clinical practice guidelines to optimize the diagnosis and treatment of this disease. This document presents consensus recommendations that resulted from the International Medical Symposia on ECD in 2017 and 2019. Herein, we include the guidelines for the clinical, laboratory, histologic, and radiographic evaluation of ECD patients along with treatment recommendations based on our clinical experience and review of literature in the molecular era.

Neoplastic Myelopathies

PURPOSE OF REVIEW

This article reviews the current classification system of primary spinal cord tumors and explores evolving diagnostic and therapeutic strategies for both primary tumors and metastatic tumors to various compartments of the spinal cord.

RECENT FINDINGS

The 2016 World Health Organization classification system allows for more precise prognostication of and therapy for spinal cord tumors and has identified new entities, such as the diffuse midline glioma, H3 K27M mutant. Whole-exome sequencing reveals that the genetic background of primary glial spinal cord neoplasms differs from that of their intracranial histologic counterparts in ways that can potentially influence therapy. Targeted and immune checkpoint therapies have improved survival for patients with melanoma and lung cancer and have simultaneously produced novel complications by enhancing radiation toxicity in some cases and by facilitating the emergence of novel autoimmune and paraneoplastic syndromes involving the spinal cord, such as neuromyelitis optica spectrum disorder and syndromes associated with anti-Hu and collapsin response mediator protein-5 (CRMP-5) antibodies. These conditions must be distinguished from tumor or infection. Epidural spinal cord compression treatment paradigms have changed with the advent of robotic surgery and advances in radiation therapy.

SUMMARY

Neoplastic myelopathies subsume a wide spectrum of pathologies. Neoplastic cord involvement may be primary or secondary and may be approached diagnostically by the particular spinal cord compartment localization. Primary spinal cord tumors account for only 2% to 4% of primary central nervous system tumors, ranging from low-grade glial neoplasms to malignant tumors. Metastatic malignancy to the epidural or leptomeningeal spaces is more common than primary cord tumors. Differential diagnoses arising in the course of evaluation for cord tumors include myelopathies related to radiation or chemotherapy and paraneoplastic syndromes, all of which are sources of significant morbidity. Knowledge of genetic syndromes and the biologic behavior of diverse histologies together with selective application of surgery, radiation, and targeted therapies can facilitate diagnosis, minimize surgical morbidity, and prolong quality of life.

Neuroendocrine manifestations of Erdheim-Chester disease

Neuroendocrine manifestations are common in Erdheim-Chester disease (ECD) patients. ECD is a rare non-Langerhans form of histiocytosis with multisystemic infiltration. The involvement of the hypothalamo-pituitary axis is common and central diabetes insipidus (CDI) is one of the most common endocrine manifestations in ECD patients. CDI is the first manifestation of ECD in 25%-48% of the cases. Suprasellar region extension, due to the infiltration of ECD lesions, can cause neurologic manifestations by mass effects, such as headache, visual disturbance, and cranial nerve palsies. Recent studies have revealed that disorders affecting anterior pituitary hormones are common in ECD patients. Secondary adrenal insufficiency, secondary hypothyroidism, (adult) growth hormone deficiency, hypogonadotropic hypogonadism, hyperprolactinemia, and hypoprolactinemia can develop as the neuroendocrine manifestations of ECD. Since the symptoms of anterior pituitary hormone deficiencies tend to be nonspecific, the diagnosis of anterior pituitary hormone dysfunctions can be delayed. Some anterior pituitary dysfunctions such as adrenocorticotropic hormone and/or thyroid-stimulating hormone deficiencies can be life-threatening without adequate hormone supplementation therapies. An endocrinological evaluation of the function of the pituitary gland should be performed at the initial diagnosis of ECD. It is important to recognize that endocrine dysfunctions can develop later during the follow-up of ECD.

Central nervous system involvement in Erdheim-Chester disease: An observational cohort study

OBJECTIVE

CNS involvement in Erdheim-Chester disease (ECD) leads to substantial morbidity and mortality. To assess CNS manifestations in a French cohort of 253 patients with ECD, we determined clinical characteristics and outcomes, including those under targeted therapies.

METHODS

This was a retrospective longitudinal study. CNS manifestations were determined by clinical examination and brain or spine MRI. Targeted therapy efficacy was assessed using global assessment from a physician and a radiologist. The study was approved by the ethics committee Comité de Protection des Personnes Ile de France III.

RESULTS

Ninety-seven of 253 patients (38%) with ECD had CNS involvement. CNS involvement was significantly associated with a younger age at diagnosis (mean 55.5 years) and at symptom onset (mean 50.5 years), as well as with the presence of the BRAF ^V600E mutation (in 77% of cases), xanthelasma (34%), and diabetes insipidus (36%). Median survival among patients with CNS involvement was significantly lower than that of patients with ECD without CNS involvement (124 months vs 146 months, p = 0.03). Seventy-four CNS MRIs were centrally reviewed, which showed 3 patterns: tumoral in 66%, pseudo-degenerative in 50%, and vascular in 18%. Targeted therapy (BRAF or MEK inhibitors) was associated with improved symptoms in 43% of patients and MRI improvement in 45%.

CONCLUSIONS

CNS manifestations are typically associated with poor prognosis in patients with ECD. Three distinct patterns can be recognized: tumoral, pseudodegenerative, and vascular.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that targeted therapy leads to clinical or imaging improvement in almost 50% of patients.

Spontaneous Intracranial Hypotension: Atypical Radiologic Appearances, Imaging Mimickers, and Clinical Look-Alikes

Spontaneous intracranial hypotension is a condition characterized by low CSF volume secondary to leakage through a dural defect with no identifiable cause. Patients classically present with orthostatic headaches, but this symptom is not specific to spontaneous intracranial hypotension, and initial misdiagnosis is common. The most prominent features of spontaneous intracranial hypotension on intracranial MR imaging include "brain sag" and diffuse pachymeningeal enhancement, but these characteristics can be seen in several other conditions. Understanding the clinical and imaging features of spontaneous intracranial hypotension and its mimickers will lead to more prompt and accurate diagnoses. Here we discuss conditions that mimic the radiologic and clinical presentation of spontaneous intracranial hypotension as well as other disorders that CSF leaks can imitate.

Neurologic and oncologic features of Erdheim-Chester disease: a 30-patient series

BACKGROUND

Erdheim-Chester disease (ECD) is a rare histiocytic neoplasm characterized by recurrent alterations in the MAPK (mitogen-activating protein kinase) pathway. The existing literature about the neuro-oncological spectrum of ECD is limited.

METHODS

We present retrospective clinical, radiographic, pathologic, molecular, and treatment data from 30 patients with ECD neurohistiocytic involvement treated at a tertiary center.

RESULTS

Median age was 52 years (range, 7-77), and 20 (67%) patients were male. Presenting symptoms included ataxia in 19 patients (63%), dysarthria in 14 (47%), diabetes insipidus in 12 (40%), cognitive impairment in 10 (33%), and bulbar affect in 9 (30%). Neurosurgical biopsy specimens in 8 patients demonstrated varied morphologic findings often uncharacteristic of typical ECD lesions. Molecular analysis revealed mutations in BRAF (18 patients), MAP2K1 (5), RAS isoforms (2), and 2 fusions involving BRAF and ALK. Conventional therapies (corticosteroids, immunosuppressants, interferon-alpha [IFN-α], cytotoxic chemotherapy) led to partial radiographic response in 8/40 patients (20%) by MRI with no complete responses, partial metabolic response in 4/16 (25%), and complete metabolic response in 1/16 (6%) by 18F-fluorodeoxyglucose (FDG)-PET scan. In comparison, targeted (kinase inhibitor) therapies yielded partial radiographic response in 10/27 (37%) and complete radiographic response in 14/27 (52%) by MRI, and partial metabolic response in 6/25 (24%) and complete metabolic response in 17/25 (68%) by FDG-PET scan.

CONCLUSIONS

These data highlight underrecognized symptomatology, heterogeneous neuropathology, and robust responses to targeted therapies across the mutational spectrum in ECD patients with neurological involvement, particularly when conventional therapies have failed.

Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a rare but increasingly recognized multi-system disorder. Its diagnosis and treatment require integration of clinical information, imaging studies, and pathology studies. Of note, ECD can now be defined as a clonal myeloid disorder due to mutations which activate mitogen-activated protein kinase (MAPK) pathways and where an inflammatory milieu is important in the pathogenesis and clinical manifestations of the disease. Biopsy demonstrating characteristic histopathologic features in addition to clinical and radiographic features, most often sclerosing long bone involvement, is required to establish a diagnosis. Detection of somatic MAPK pathway mutations can also assist in the differential diagnosis of ECD and related histiocytic neoplasms. Also, genetic analysis establishing BRAF and RAS mutational status is critical in all ECD patients, as these features will impact therapy with MAPK inhibition. Therapy is recommended at diagnosis in all patients, except for those patients with minimally symptomatic disease. Prospective therapeutic trials are essential to furthering therapeutic progress in ECD.

Choreo-Athetosis and Ataxia as Leading Features in a Case of Erdheim-Chester Disease

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Erdheim-Chester disease mimicking lumbar nerve schwannoma: case report and literature review

Introduction

Erdheim-Chester disease (ECD) is a rare, non-Langerhans cell histiocytosis. The clinical spectrum of ECD is diverse, varying from asymptomatic focal lesion to life-threatening multisystem infiltration. Neurological manifestations of ECD are common, mostly due to the involvement of the central nerve system. However, spinal nerve or peripheral nerve involvement has rarely been mentioned.

Case presentation

Herein, we present a case of a 32-year-old female patient complaining about radiating pain on the front and lateral side of her left thigh for 2 months. Spinal MRI with contrast enhancement showed a space-occupying lesion on the left L3/L4 intervertebral foramen, indicating an initial diagnosis of lumbar nerve schwannoma. The patient underwent surgery to remove the mass and decompress the lumbar nerve. Postoperative histological examination revealed the diffuse infiltration of foamy histiocytes that were CD68+, CD163+, and CD1a- on immunostaining, which confirmed the diagnosis of Erdheim-Chester disease. The radiating pain was gradually alleviated and PET-CT was performed but showed no further involvement of ECD.

Discussion

To the best of our knowledge, this is the first case of ECD demonstrated as an infiltrative mass on the spinal nerve, with imaging manifestations and compression symptoms similar to those of peripheral nerve schwannoma.

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.