Consensus guidelines for the diagnosis and clinical management of Erdheim-Chester disease

Unusual orbital, scleral and choroidal findings in Erdheim-Chester disease: a case report

This case report highlights a unique presentation of Erdheim-Chester Disease (ECD) with bilateral scleral lesions, choroidal infiltration, and extensive sinus involvement. It is the first case report where the diagnosis was confirmed through a scleral biopsy after an initial presentation of a unilateral nodular scleritis. There was a gradual disease progression and ocular examination later revealed bilateral subconjunctival hyperemic lesions and mild exophthalmos, ophthalmoplegia, and extensive choroidal infiltration. Infiltration of the frontal and maxillary sinus was present and extended into the nasal cavity and both orbits. The diagnostic work-up is described in detail. Current treatment options are analyzed. It is emphasized that the ophthalmologist can play a crucial role in the diagnosis of ECD, given the substantial prevalence of orbital and ocular symptoms. The overall prognosis for ECD remains unfavorable, particularly in cases with orbital involvement. This case underscores the complexity and importance of a multidisciplinary approach in managing ECD.

Clinical characterization of aortitis and periaortitis: study of 134 patients from a single university hospital

Aortitis and periaortitis refer to the inflammation of the aortic wall and the surrounding tissues. Both conditions are associated with various diseases and express nonspecific manifestations. Early diagnosis and treatment are crucial to improve the prognosis of the disease. This study aimed to assess the causes and main clinical features of aortitis and periaortitis in patients from a single centre in Spain. Observational, retrospective study of patients diagnosed with aortitis or periaortitis at a Spanish referral center over the last decade. 134 patients (87 female; mean age of 55.1 ± 9.1 years) were recruited, 132 of which had aortitis and two periaortitis. Aortitis was associated with giant cell arteritis (n = 102), Takayasu's arteritis (n = 6), IgG4-related disease (n = 6), infectious diseases (n = 3), malignancy (n = 1), drugs (n = 1), isolated aortitis (n = 1), and other immune-mediated inflammatory diseases (IMIDs) (n = 12). IMIDs included were Sjögren's syndrome (n = 2), sarcoidosis (n = 2), rheumatoid arthritis (n = 2), axial spondyloarthritis (n = 2), inflammatory bowel disease (n = 1), primary biliary cirrhosis (n = 1), idiopathic pulmonary fibrosis (n = 1), and polyarteritis nodosa (n = 1). Periaortitis was due to idiopathic retroperitoneal fibrosis in both cases. Imaging techniques used for diagnosis included 18F-FDG PET/CT scan (n = 133), CT-angiography (n = 44), and/or MRI-angiography (n = 33). Polymyalgia rheumatica (52.2%) and asthenia (53.7%) were the most common manifestations, followed by limb claudication (23.9%) and inflammatory back pain (26.9%). Acute-phase reactants were typically increased. Aortitis is a common condition and may be associated with multiple non-infectious diseases. Its clinical presentation is often unspecific, requiring a high level of suspicion to get an early diagnosis and treatment.

Histiocytosis Advancements Parallel Ophthalmic Innovations: The LXXXI Edward Jackson Memorial Lecture

PURPOSE

To highlight innovations in ophthalmic oncology through histiocytosis advancements.

DESIGN

Perspective and retrospective review.

METHODS

The literature outlining the recent advancements in histiocytosis and ocular oncology was reviewed and combined with trial data and personal recollection. Intersections between these two fields were discussed.

RESULTS

The understanding of genetic mutations in disease-both in which cells they occur and the timing of mutation development-has expanded in tandem for the fields of ophthalmic oncology and histiocytosis. Similarly, advancements in diagnostic and treatment technology in one field can help patients in the other. For example, in one study, cell-free DNA testing reliably detected mutations in 14 of 18 (78%) patients with suspected histiocytosis. This technique has also been used in ophthalmic oncology as an alternative to invasive biopsy to avoid the risk of tumor externalization, vision impairment, and other side effects. These and other advancements have allowed both fields to utilize targeted agents to successfully treat diseases with an actionable mutation; or deliver more targeted chemotherapy via the intraarterial technique.

CONCLUSIONS

The explosion of molecular genetics technology and targeted therapies has revolutionized cancer treatment, including histiocytosis and ophthalmic oncology. Recent progress in both fields has shown how these seemingly disparate areas have many intersections, and this speaks to the collaborative spirit that is inherent in clinical research.

Langerhans Cell Histiocytosis and Other Histiocytic Lesions

BACKGROUND

Histiocytoses, including Langerhans cell histiocytosis (LCH), comprise a diverse group of histiocytic disorders characterized by the abnormal accumulation and proliferation of histiocytes in various tissues or organs throughout the body, ranging from benign, self-limited conditions to aggressive malignancies and systemic inflammatory syndromes. These lesions present unique diagnostic challenges due to their broad spectrum of clinical presentations, overlapping histopathological and immunophenotypical features, and genetic complexity.

METHODS

This review analyzes major histiocytic lesions, focusing on their epidemiology, clinical presentations, histologic and immunophenotypic features, and genetic characteristics to facilitate accurate diagnosis and differentiation among these histiocytoses.

RESULTS

LCH, a well-recognized lesion, can affect various organ systems and necessitates differentiation from other types of histiocytoses such as Erdheim-Chester disease (ECD), Rosai-Dorfman-Destombes disease (RDD), and cutaneous and mucocutaneous non-Langerhans cell histiocytoses. Some histiocytic lesions, such as histiocytic sarcoma, are inherently malignant, while others, like hemophagocytic lymphohistiocytosis (HLH), manifest as severe, potentially life-threatening systemic inflammatory syndromes. Recent molecular genetic studies revealed recurrent genetic alterations in the MAPK pathway, such as BRAF V600E and MAP2K1 in LCH and ECD, and KRAS, NRAS, and MAP2K1 mutations in a subset of RDD. Malignant histiocytoses frequently show alterations in tumor suppressor genes like TP53 and CDKN2A.

CONCLUSION

Precise classification of histiocytic lesions relies on a comprehensive diagnostic approach that integrates clinical, histologic, immunophenotypic, and genetic data. Recent genetic advances shed light on these conditions' unique but occasionally overlapping pathogenic mechanisms. Molecular genetics advancements continue to refine diagnostic accuracy and present new therapeutic targets, especially for aggressive or treatment-resistant cases.

Erdheim-Chester disease: Comprehensive insights from genetic mutations to clinical manifestations and therapeutic advances

Erdheim-Chester disease (ECD) is an extremely rare non-Langerhans cell disorder that is believed to include both inflammatory and neoplastic characteristics. It is caused due to genetic mutations in proto-oncogenes like BRAF and MEK, while immunological pathways have an essential role in the onset and progression of the disease. Despite its rarity, ECD poses significant diagnostic and therapeutic challenges due to its heterogeneous clinical presentation and limited understanding of its underlying pathophysiology. Multiple organs can be affected, with the most frequent being long bones, central nervous system and retro-orbital abnormalities, pericardial and myocardial infiltration, interstitial lung disease, retroperitoneal fibrosis, and large blood vessel aberrations. Here, in this review, we comprehensively underline the current knowledge of ECD, including its epidemiology, clinical manifestations, genetics, pathophysiology, diagnostic modalities, and treatment options. By synthesizing existing literature and highlighting areas of ongoing research, this review aims to provide clinicians and researchers with a comprehensive understanding of ECD and guide future directions for improved patient care and outcomes.

Recent advances in therapeutic strategies of Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a rare form of non-LCH characterized by excessive accumulation of histiocytes in various tissues, leading to significant morbidity. The estimated prevalence of ECD is low, with fewer than 1000 cases reported globally, yet it presents considerable clinical challenges due to its heterogeneous manifestations, which include bone pain, cardiovascular complications, and neurological symptoms. Traditional treatment approaches, primarily involving corticosteroids and chemotherapy, have limitations, including inconsistent responses and significant side effects. Recent advances in understanding the pathogenesis of ECD, particularly the role of the BRAF V600E mutation, have led to the exploration of novel therapeutic strategies, such as targeted BRAF inhibitors, MEK and mTOR inhibitors, and other immunotherapies, which offer promise in improving patient outcomes. The review further explores clinical manifestations, and radiographic features of Erdheim-Chester disease, and discusses treatment strategies, current clinical studies in the field of ECD. By integrating these aspects, this review aims to provide a thorough understanding of ECD and its evolving treatment landscape, ultimately contributing to improved patient outcomes.

Erdheim-Chester Disease with Pancreatic Enlargement Observed Using Contrast-enhanced Endoscopic Ultrasonography

We herein report an unusual case of Erdheim-Chester disease (ECD), a rare non-Langerhans cell histiocytosis, and emphasize its unique presentation and diagnostic challenges. Our patient exhibited uncommon symptoms and significant organ involvement, particularly pancreatic enlargement that is not typically associated with ECD. Contrast-enhanced harmonic endoscopic ultrasonography (CEH-EUS) and EUS-fine needle aspiration (EUS-FNA) play crucial roles in the comprehensive assessment of the disease, demonstrating their superiority in identifying and characterizing elusive ECD lesions. This is the first report to document pancreatic lesions in patients with ECD evaluated using CEH-EUS. EUS-FNA is valuable for diagnosing rare diseases, including ECD, with diffuse pancreatic enlargement.

Progress in investigating pituitary stalk lesions: A review

Pituitary stalk lesions are uncommon and are typically identified through pituitary magnetic resonance imaging and screening for causes of diabetes insipidus. Recent literature indicates that pituitary stalk lesions primarily manifest as pituitary stalk interruption syndrome and thickening of the pituitary stalk. The etiology of these lesions is complex and can be divided into major categories: congenital disorders, inflammatory or infectious diseases, and tumors. Therefore, achieving accurate diagnosis, differential diagnosis, and treatment for pituitary stalk lesions is crucial. This article aims to classify pituitary stalk lesions and delve into the latest research on their etiology, pathological mechanisms, clinical manifestations, diagnosis, and treatment of associated diseases.

A Rare Case of Isolated Central Nervous System Neoplasm With Histiocytic Features

This paper discusses a rare case of a 49-year-old female diagnosed with a central nervous system-isolated neoplasm with histiocytic features, classified as histiocytic neoplasm, not otherwise specified (NOS). Despite comprehensive histopathological and genetic studies, accurately diagnosing the case proved challenging. Initial surgical findings and frozen biopsy suggested a low-grade glioma; however, subsequent immunohistochemistry and genetic analysis excluded known histiocytic subtypes such as ALK-positive histiocytosis and Erdheim-Chester disease. The patient's condition improved following occupational rehabilitation therapy for right upper motor weakness, as well as anticonvulsant and radiation therapy, and her neurological condition remains stable. This case underscores the diagnostic challenges of Histiocytic Neoplasms and the necessity for interdisciplinary collaboration and sophisticated diagnostic techniques.

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.

Isolated Osseous Rosai Dorfman Disease of Foot Bones. Report of a Patient Misdiagnosed and Treated as Chronic Osteomyelitis

Isolated osseous involvement without lymphadenopathy is a rare manifestation of Rosai-Dorfman disease. It clinically and radiologically mimics infections and primary bone tumors. The present report describes a 9-year-old girl with multifocal monomelic osseous involvement as an isolated manifestation. She presented with lytic lesions in the left proximal phalanx of the great toe and head of the second metatarsal unaccompanied by disease elsewhere. She was treated outside as chronic osteomyelitis. After 9 months, the swelling recurred, and a repeat biopsy was suggestive of Rosai-Dorfman disease. This report highlights the diagnostic challenges in patients with extra nodal isolated bone involvement, especially on small biopsies.

BRAF V600E mutation and high expression of PD-L1 in Rosai-Dorfman disease: case report and review of the literature

BRAF V600E mutations are frequently found in histiocytic/dendritic cell neoplasms such as Erdheim-Chester disease (ECD) and Langerhans cell histiocytosis (LCH), but few reports have also described BRAF mutations in Rosai-Dorfman disease (RDD), and even these cases may predominantly represent mixed histiocytosis. BRAF mutations have been studied in histiocytic/dendritic cell neoplasms and described to be associated with increased risk of relapse and long-term consequences, but few studies have examined BRAF V600E mutation in RDD, which is recognized as a neoplasm given the high frequency of MAPK pathway alterations. Here, we report a case of BRAF V600E-mutated RDD in a patient who presented with generalized lymphadenopathy. During our evaluation of this patient, we also found expression of PD-L1 in neoplastic histiocytes. During our review period, only few cases of RDD reported to harbor BRAF mutation or were evaluated for the expression of PDL1 by neoplastic cells. Given the potential challenges in distinguishing RDD from other histiocytic/dendritic cell neoplasms, including mixed histiocytosis with similar clinicopathological manifestations, we will discuss the current state of knowledge regarding the frequency and clinical impact of BRAF V600E in RDD, as well as the role of BRAF mutations in RDD pathogenesis. Distinction of BRAF V600E mutated histiocytic/dendritic cell neoplasms requires consideration of distinctive histopathological and immunophenotypic findings in appropriate clinical and radiologic setting. Given the increasing use of BRAF inhibitors as well as checkpoint blockade inhibitors to treat a number of cancers, we will discuss the clinical implications of the presence of BRAF V600E mutation and PD-L1 expression in RDD.

Expert consensus on the off-label use in China of drugs for rare hematologic diseases (2024 edition)

Drug package inserts are a crucial foundation for clinical medication practices and serve as the legal basis for guiding rational drug use and ensuring patient safety and efficacy. As rare disease treatments evolve, current package inserts often need to meet the clinical requirements for treating such conditions, frequently resulting in off-label drug use. This consensus is derived from discussions between Guangdong Pharmaceutical Association Hematologic Rare Diseases Group experts. The consensus aims to provide a framework and reference for the clinical application of off-label drug use in treating rare hematologic diseases.

Subfoveal Choroidal Thickness in Patients with Histiocytosis and Multimodal Imaging Features of Choroidal Infiltrates

PURPOSE

To evaluate choroidal findings in patients with histiocytosis, including subfoveal choroidal thickness (SFCT), and multimodal imaging in eyes with choroidal infiltrates visible by ophthalmoscopy and determine if abnormalities change with histiocytosis-directed (kinase inhibitor) therapy.

DESIGN

Retrospective comparative study at single tertiary cancer referral center.

PARTICIPANTS

Ninety-one patients with histiocytosis and 41 age- and sex-matched controls.

METHODS

Clinical examination, fundus photography, and OCT were used to assess choroidal findings. Clinically evident choroidal infiltrates by ophthalmoscopy were recorded, and choroidal vascular architecture was qualitatively examined. Subfoveal choroidal thickness and was measured using enhanced depth imaging spectral domain OCT from the outer portion of Bruch membrane to the choroidal scleral interface.

MAIN OUTCOME MEASURES

Subfoveal choroidal thickness was compared with matched controls; that secondary outcome was change in SFCT on histiocytosis-directed (kinase inhibitor) therapy. Multimodal imaging of choroidal infiltrates was visible by ophthalmoscopy.

RESULTS

One hundred and eighty-two eyes of 91 patients (46 males, 45 females) with histiocytosis (Erdheim-Chester 35, Rosai-Dorfman 21, xanthogranuloma 7, mixed histiocytosis 11, Langerhans cell histiocytosis 15, and other 2) were examined. In patients with histiocytosis, the mean SFCT was 336.2 ± 94.9 μm compared with 250.3 ± 60.7 μm in the control group (P < 0.0001). Notably, 69% of patients with histiocytosis had SFCT >275 μm compared with 27% in controls (P < 0.0001). Subtype of histiocytosis, sites of bone or central nervous disease, posterior segment/other sites of ophthalmic disease, or mutational profile did not correlate with SFCT. In a subgroup analysis of 35 patients naïve to prior treatment, with >6 months follow-up, the proportion of SFCT >275 μm significantly decreased (P = 0.0016) on histiocytosis-directed (kinase inhibitor) therapy. Notably, 19.8% of patients had clinically evident choroidal infiltration: majority were yellow creamy, geographic, located posteriorly and hyperautofluorescent; with enlarged Haller vein bordering the infiltrate, choriocapillaris compression and loss of choroidal architecture by OCT.

CONCLUSIONS

In this cohort, 19.8% of patients with histiocytosis had clinically evident infiltration of their choroid. Furthermore, the majority of patients with histiocytosis had increased SFCT compared with age- and sex-matched controls. The thickened choroid decreases on histiocytosis-directed (kinase inhibitor) therapy and may be a marker of response to systemic treatment.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Erdheim-Chester Disease: A Case Report Exploring Multisystemic Involvement

Erdheim-Chester disease (ECD) is a rare, multisystemic, non-Langerhans cell histiocytic neoplasm predominantly affecting middle-aged males in their fifth to seventh decades of life. It often presents with nonspecific symptoms, leading to a delay in its diagnosis. We report a case of an 85-year-old male with multisystemic manifestations, including retroperitoneal, skeletal, vascular, cardiac, orbital, and central nervous system (CNS) involvement. Imaging revealed characteristic findings such as bilateral osteosclerosis, perirenal infiltration (hairy kidney sign), and dural-based intracranial masses. Histopathological analysis confirmed the diagnosis, identifying CD68+ histiocytes and the BRAFV600E mutation. The patient was managed initially by Internal Medicine and later referred to Hemato-Oncology for further treatment. This report highlights the importance of maintaining a high index of suspicion for this rare disorder, as well as adopting a multidisciplinary approach toward its treatment, integrating clinical, radiological, and histopathological data.

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.

Ocular findings in patients with histiocytosis and association with clinical and molecular features

BACKGROUND/AIMS

Ocular manifestations of histiocytosis and their genetic underpinnings are poorly characterised. This study characterises ocular sites of histiocytosis, notate genetic alterations and correlates to histiocytosis clinical features including subtype and sites of disease.

METHODS

Prospective registry-based study of predominantly adult histiocytosis patients at a single-institution tertiary referral centre. 180 eyes of 90 patients (46 males, 44 females) with histiocytosis (Erdheim-Chester disease 34, Rosai-Dorfman 20, xanthogranuloma 7, mixed histiocytosis 13, Langerhans cell histiocytosis (LCH) 15, ALK-positive histiocytosis 1). Ocular findings were categorised by the structure involved. Histiocytosis subtype, sites of disease and genetic status were correlated to ocular findings.

RESULTS

Ocular disease was present in more than half the histiocytosis patient cohort and occurred with other disease sites. Ocular findings were statistically significantly different across histiocytic subtypes with LCH subtypes having the lowest proportion of ocular findings (7%) and all other subtypes having rates of ocular findings which were five times that of patients with LCH (p=0.0009). Of patients with ocular findings, 41% of patients reported ocular symptoms and were significantly more in the group with ocular disease present versus those patients without ocular involvement. The presence of ocular findings was not statistically different by BRAFV600E, MAP2K1 or RAS isoform mutational status.

CONCLUSIONS

Ocular disease is a common feature of histiocytosis with significant visual symptomatology and occurrence in tandem with multisystem sites. Ocular findings vary by histiocytic subtype. The mutational profile of the cohort reflects known mutations in this clinical population, with no specific driver mutation associated with ocular disease.

Unveiling the enigma: Navigating extranodal Rosai-Dorfman disease in the maxilla - A teen's journey

Rosai-Dorfman disease (RDD), a rare histiocytic disorder, typically manifests as widespread lymphadenopathy. We present a unique case of extranodal RDD in a 14-year-old with a solitary maxillary lesion and mild bilateral submandibular lymphadenopathy. Clinical, radiological, and histopathological assessments confirmed RDD, highlighting the importance of a comprehensive approach. Immunohistochemistry, including CD68, CD45, CD 1a, and S100, played a crucial role in diagnosis. Differential diagnoses encompassed Langerhans cell histiocytosis, Erdheim-Chester disease, lymphomas, and histiocytic sarcoma, necessitating meticulous evaluation. Surgical excision was performed due to bone involvement, leading to successful healing in six months. Our case underscores the significance of a multidisciplinary and scientific approach for accurate RDD diagnosis and management, especially in atypical intraoral presentations.

Total Hip Replacement in a Patient with Erdheim-Chester's Disease: A Case Report

CASE

Erdheim-Chester's disease (ECD) is a rare multisystem disorder considered as a neoplasm of non-Langerhans cell histiocytes. We report a case of uncemented total hip arthroplasty in a 74-year-old patient with ECD for femoral neck fracture with pathological involvement of distal metaphysis and diaphysis. We reviewed the literature on bony involvement.

CONCLUSION

Adequate osseointegration was achieved in our case; however, longer follow-up is essential. Vigilant reporting of bony involvement, such as pathological fractures, fracture healing, deformities, osteosynthesis, and outcome of joint replacement surgeries, is needed in ECD-like bone diseases.

Rare severe constrictive pericarditis complication in Erdheim-Chester disease: A case report and literature review

Erdheim-Chester disease (ECD) is a rare, non-Langerhans cell histiocytosis with diverse clinical features. It is characterized by systemic histiocyte infiltration of the bone, skin, central nervous system, lung, kidney, and cardiovascular system. Pericardial involvement is frequently revealed through either pericardial effusion or pericardial thickening in patients with ECD. Although most patients remain asymptomatic, progressive pericarditis, effusion, or cardiac tamponade may occur. Herein, we report a rare and unusual presentation of ECD in a 51-year-old man who experienced severe constrictive pericarditis. The patient presented with uncontrolled fluid retention and heart failure. After the diagnosis of ECD, interferon alpha treatment was administered. The patient recovered dramatically with decreased pleural and pericardial effusion, as well as improvements in the echocardiographic signs of constrictive pericarditis. Despite several therapeutic options described in the literature for managing ECD-related pericardial disease, a standard treatment has not been established. This report highlights the importance of early treatment based on accurate diagnosis of an unusual ECD complication.

Imaging in Erdheim-Chester Disease

Erdheim-Chester disease (ECD) is a rare, multisystemic, inflammatory, non-Langerhans cell histiocytic neoplasm. The discovery of recurrent and somatic mutations in the mitogen-activated protein kinase signaling pathway, most commonly BRAFV600E, has led to a reclassification of ECD from an inflammatory disorder to a neoplastic process. It is now included in the revised 2016 World Health Organization classification of hematopoietic tumors and in the Langerhans group in the revised 2016 Histiocytosis Classification of the Histiocyte Society. When symptomatic, ECD most commonly manifests with bone pain and fatigue. Also, neurologic manifestations, central diabetes insipidus, exophthalmos, and periorbital xanthelasma-like lesions are frequently encountered. Pathologic findings may vary depending on the site of biopsy and may display a spectrum of features. Thus, due to the diverse clinical presentation and variable histologic findings, imaging can often show the first sign of the disease. Radiologic findings are, however, interpreted in conjunction with clinical and histologic findings to establish the diagnosis of ECD. From providing classic findings that facilitate diagnosis to helping radiologists determine the extent of disease and predicting a prognosis, the role of radiology in ECD has evolved with the understanding of the disease itself. Insights into the molecular pathogenesis and the development of targeted therapeutic agents along with approval of vemurafenib and cobimetinib have necessitated revision of the guidelines for the management of ECD. The authors discuss various radiologic findings of ECD and differential diagnoses by using an organ system-based approach and briefly describe the revised consensus recommendations for evaluation, diagnosis, and treatment based on the International Medical Symposia on ECD from a radiologist's perspective. ©RSNA, 2024 Supplemental material is available for this article. The full digital presentation is available online.

Atypical case of Erdheim-Chester Disease involving bilateral orbits

Purpose

We report a patient who initially visited the ophthalmology clinic for a vision loss diagnosed with Erdheim-Chester Disease (ECD).

Observations

ECD is a rare non-Langerhans cell histiocytosis characterized by multisystemic organ involvement and poor prognosis. Our patient had complete vision loss due to prominent orbital involvement before any systemic symptoms appeared. This case demonstrates variable clinical manifestations of ECD.

Conclusions and importance

Painless bilateral proptosis with poor response to steroid treatment should prompt consideration for ECD and systemic evaluation. In addition, in the absence of typical clinical manifestations, a thorough evaluation of the biopsy can be crucial for an accurate diagnosis.

Erdheim-Chester Disease With Eyelid and Orbital Involvement: A Review of Treatment Modalities at One Institution From 2014 to 2022

PURPOSE

To review all cases of Erdheim-Chester disease (ECD) with orbital involvement treated at Bascom Palmer Eye Institute in Miami, Florida from 2014 to 2022 and compare presentations, treatment modalities, and outcomes.

METHODS

A retrospective chart review of all patients diagnosed with ECD who presented to Bascom Palmer Eye Institute from 2014 to 2022 was performed. Data collected included demographics, pretreatment history and ophthalmic examination, pathology report, treatment, subsequent examination, and relevant laboratory results. Histopathology, treatments, and outcomes were reviewed and compared between patients.

RESULTS

Four cases were included. Primary treatments included vemurafenib (n = 2), cobimetinib (n = 1), and prednisone (n = 1). All patients demonstrated improvement of ophthalmic symptoms. Vemurafenib was the only medical treatment that was tolerated well and resulted in significant improvement in proptosis despite some reported dry eye; all other medications were discontinued due to intolerable side effects.

CONCLUSIONS

BRAF inhibitors such as vemurafenib have been used as novel therapy in the treatment of ECD. Vemurafenib demonstrated its utility in reducing proptosis in ECD patients at one ophthalmic institution. Vemurafenib may be a favorable treatment option for BRAF -positive ECD patients presenting with orbital disease.

Clinical phenotype of adult-onset systemic histiocytosis harboring BRAF in-frame deletions

Not available.

Erdheim-Chester disease: An elusive diagnosis in a 50-year-old Ethiopian man presenting with diffuse sclerotic bone lesion

Key Clinical Message

Diagnosis of Erdheim-Chester disease (ECD) requires the clinician to be familiar with its various manifestations, classic radiologic and histologic features. This case highlights the significance of considering ECD in any patient presenting with bone pain and symmetric osteosclerosis of long bones of extremities to allow for early diagnosis and treatment.

Abstract

Erdheim-Chester disease (ECD) is a rare non-Langerhans histiocytic disorder with diverse clinical manifestations, ranging from indolent, localized presentation to life-threatening, multi-systemic disease. Delayed or erroneous diagnosis is common. The presence of classic radiographic finding along with foamy histiocytes that is positive for CD68 but negative for CD1a on histologic examination establishes the diagnosis. We report a second case of ECD from Ethiopia. A 50-year-old Ethiopian man presented with a 13-year history of bilateral lower leg bone pain, cold intolerance, somnolence, constipation, impotence, decreased libido, and secondary infertility. The diagnosis was suspected when skeletal X-ray revealed bilateral symmetric sclerosis of metadiaphysis of femur, tibia, and humerus. The demonstration of foamy histiocytes that were positive for CD68 but negative for CD1a on histologic examination with immunohistochemical staining confirmed the diagnosis. Evaluation for the extent of the disease revealed coated aorta sign, hairy kidney sign, and cystic lesion with ground glass opacity of lung, primary hypothyroidism, and hypergonadotropic hypogonadism. ECD is rare histiocytic neoplasm with wide range of clinical features which often delay the diagnosis. Clinician should be mindful of the various presentations and the classic radiographic and histologic features of ECD. This case highlights the significance of entertaining ECD in any patient presenting with lower leg bone pain and symmetric osteosclerosis of long bones of lower extremities to allow for early diagnosis and treatment.

Erdheim-Chester Disease Presenting as Bilateral Facial Masses: A case report and review of literature

Erdheim-Chester disease (ECD) is a rare form of non-Langerhans cell histiocytosis with unknown aetiology. It is recently recognised to be neoplastic with genetic mutations affecting the mitogen-activating protein kinase pathway. We report a 49-year-old female patient who initially presented in 2012 to a tertiary care centre in Muscat, Oman, with bilateral facial masses. These were removed but later recurred over a period of 10 years. She then presented with xanthelasmas, bone lesions, secondary infertility due to hypothalamic hypogonadism, diabetes insipidus and Hashimoto's hypothyroidism. The facial masses were biopsied and they showed classic morphological features in the form of diffuse infiltration by foamy histiocytes with scattered Touton type of giant cells, patchy lymphocytic infiltrates and dense fibrosis. The patient is stable and is being followed-up. The presented ECD case is particularly interesting due to the recurrent bilateral facial masses. To the best of the authors' knowledge, this is the first documented case in Oman.

Advancements in the understanding and management of histiocytic neoplasms

Histiocytic neoplasms are rare diseases involving macrophages, dendritic cells, and monocytes. They include Langerhans cell histiocytosis (LCH), Erdheim-Chester disease (ECD), Rosai-Dorfman disease (RDD), juvenile xanthogranuloma (JXG), and histiocytic sarcoma. Histiocytic neoplasms are characterized by varied clinical courses and prognoses, necessitating a nuanced understanding of their classification, epidemiology, and clinical manifestations. Genetic studies have revealed somatic mutations, predominantly in the MAPK pathway, suggesting a clonal neoplastic nature. This review covers the current understanding of histiocytic neoplasms, molecular pathophysiology, with a particular focus on mutations in genes such as BRAF, MAP2K1, and the PI3K-AKT signaling pathways, and evolving treatment strategies, especially focusing on LCH, ECD, RDD, and JXG. The treatment landscape has evolved with advancements in targeted therapies. BRAF inhibitors, such as vemurafenib and dabrafenib, have shown efficacy, especially in high-risk LCH cases; however, challenges remain, including relapse post-treatment discontinuation, and adverse effects. MEK inhibitors have also demonstrated effectiveness, and cobimetinib has recently been approved for use in adults. Further research is required to determine the optimal treatment duration and strategies for managing therapy interruptions. Advancements in molecular genetics and targeted therapies have revolutionized the management of histiocytic neoplasms. However, ongoing research is crucial for optimizing patient outcomes.

Advances in Understanding and Management of Erdheim-Chester Disease

Erdheim Chester Disease (ECD) is a rare histiocytic disorder marked by infiltration of organs with CD68+ histiocytes. ECD stems from mutations of BRAF and MAP2K1 in hematopoietic stem and progenitor cells (HSPCs), which further differentiate into monocytes and histiocytes. Histopathology reveals lipid-containing histiocytes, which test positive for CD68 and CD133 in immunohistochemistry. Signs and symptoms vary and depend on the organ/s of manifestation. Definitive radiological results associated with ECD include hairy kidney, coated aorta, and cardiac pseudotumor. Treatment options primarily include anti-cytokine therapy and inhibitors of BRAF and MEK signaling.

Selected Case From the Arkadi M. Rywlin International Pathology Slide Seminar: Involvement of Skin and Soft Tissue by Erdheim-Chester Disease

Erdheim-Chester disease is a rare form of non-Langerhans cell histiocytosis that preferentially involves long bones but can affect a variety of other organs. Initial presentation with extraskeletal involvement is not unusual and is most commonly observed in the central nervous system, heart, retroperitoneum, lungs, and skin. Initial presentation of the disease as a subcutaneous soft tissue mass is exceedingly rare and may pose difficulties for diagnosis. We describe a case of Erdheim-Chester disease that initially presented as a cutaneous and subcutaneous soft tissue mass in the right posterior shoulder of a 52-year-old man.

Erdheim-Chester Disease presenting with constrictive pericarditis: A case report and review of the literature

Erdheim-Chester Disease (ECD) is a rare form of histiocytosis characterized by xanthomatous infiltration of affected organs. We present a case of a 62-year-old man with ECD initially presenting with constrictive pericarditis. Comprehensive imaging revealed systemic involvement, including the skeleton, orbit, pituitary, lung, kidney, and retroperitoneum, despite the absence of related symptoms. The diagnosis of ECD was eventually confirmed through histopathological evidence from a CT-guided biopsy. The patient responded well to interferon-α2b treatment, with gradual symptom amelioration and improvement in imaging and laboratory findings over a 5-month follow-up period. This case highlights the importance of considering ECD in the differential diagnosis of constrictive pericarditis and the utility of multimodal imaging for accurate diagnosis and management of this rare disease. The patient's positive response to treatment also highlights the potential for effective management of ECD, particularly with early diagnosis and intervention.

Orbital histiocytosis; From A to Z

PURPOSE

Histiocytosis is one of the most challenging diseases in medical practice. Because of the broad spectrum of clinical manifestations, systemic involvements, unknown etiology, and complex management, different types of histiocytosis are still a big question mark for us. Orbital histiocytosis is characterized by the abnormal proliferation of histiocytes in orbital tissues. It could affect the orbit, eyelid, conjunctiva, and uveal tract. Orbital histiocytosis can cause limited eye movement, proptosis, decreased visual acuity, and epiphora. In this study, we review the novel findings regarding the pathophysiology, diagnosis, and treatment of different types of histiocytosis, focusing on their orbital manifestations.

METHOD

This review was performed based on a search of the PubMed, Scopus, and Embase databases or relevant published papers regarding orbital histiocytosis on October 9th, 2023. No time restriction was proposed, and articles were excluded if they were not referenced in English.

RESULTS

391 articles were screened, most of them being case reports. The pathophysiology of histiocytosis is still unclear. However, different mutations are found to be prevalent in most of the patients. The diagnostic path can be different based on various factors such as age, lesion site, type of histiocytosis, and the stage of the disease. Some modalities, such as corticosteroids and surgery, are used widely for treatment. On the other hand, based on some specific etiological factors for each type, alternative treatments have been proposed.

CONCLUSION

Significant progress has been made in the detection of somatic molecular changes. Many case studies describe various disease patterns influencing the biological perspectives on different types of histiocytosis. It is necessary to continue investigating and clustering data from a broad range of patients with histiocytosis in children and adults to define the best ways to diagnose and treat these patients.

Erdheim-Chester disease as complex clinical presentation and diagnosis: A case report and concise review of literature

RATIONALE

Erdheim-Chester disease (ECD) is a rare multisystemic disease characterized by the infiltration of multiple organs by foamy CD68 + CD1a-histiocytes. The genetic background consists of gain-of-function somatic mutations in the mitogen-activated protein kinase pathway. The purpose of the present paper is to make a contribution to the scientific literature on ECD by reporting our experience with a complex clinical case report, along with a concise review of the literature. We discussed the unusual clinical presentation, the complex diagnostic process and the comparison with other published cases.

PATIENT CONCERNS

A 70-year-old man presented with arthralgia due to multiple bone areas of sclerosis, first diagnosed with metastases of a prostatic neoplasm. Sequential thorax-abdomen, femoral and homer contrast-enhanced computed tomography (CT) showed pericardial effusion, pulmonary fibrosis, and perirenal fibrous tissue as "hairy kidneys." He underwent. Three bone biopsies were unsuccessful to reach diagnosis.

DIAGNOSES

A xanthelasma biopsy showed histopathological signs compatible with ECD; genetic analysis showed the mutation BRAFV600E.

INTERVENTIONS

The patient underwent targeted therapy with vemurafenib (BRAF-inhibitor), discontinued 2 weeks later due to the onset of a diffuse erythematous papular rash on the trunk and limbs.

OUTCOMES

At the 1-year follow-up, there was only progression of chronic kidney disease (CKD).

LESSONS

The present case report describes how ECD diagnosis could represent a challenge for clinicians, owing to its heterogeneous clinical presentation. Early diagnosis followed by prompt therapy is essential for modifying the natural history of the disease.

Rare Case of a Patient With Erdheim-Chester Disease Presenting With Atypical Breast Involvement

Erdheim-Chester disease (ECD) is a rare multisystem disorder characterized by mitogen-activated protein kinase (MAPK) pathway mutations. Herein, we present a unique case of ECD in a 79-year-old female with predominant breast nodules. Comprehensive imaging and histopathological evaluations confirmed the diagnosis. Mammography and ultrasonography revealed multiple hyperdense circumscribed nodules with coalescing masses and blurred margins. Core biopsy revealed infiltrating foamy cluster of differentiation (CD) 68+ and CD1a+ histiocytes. Because the tumor was negative for the BRAF V600E mutation, treatment with interferon-α was initiated. This case highlights the diagnostic challenges associated with ECD, the rarity of breast involvement, and the importance of considering ECD in the differential diagnosis of atypical breast lesions. Comprehensive imaging, histopathology, and genetic testing are essential for accurate diagnosis and treatment decision-making in ECD. Further research and awareness are required to improve recognition and management of this rare disease.

Erdheim‑Chester disease of multisystem involvement with delayed diagnosis: A case report and literature review

Erdheim-Chester disease (ECD) is a rare tumor of histiocytic origin, characterized by foamy or lipid-laden histiocytes mixed or surrounded by fibrosis that infiltrate multiple organs. Misdiagnosis is common due to the diversity of clinical presentations. The present study reported a case of ECD with the involvements of bone, cardiac, aorta and retroperitoneum. The patient had no obvious clinical symptoms and no noteworthy foamy histiocytes or Touton giant cells were found on pathological examination, delaying the diagnosis. The patient was a young male found to have pericardial effusion on physical examination, and computed tomography (CT) revealed soft tissue infiltrates in the retroperitoneum and around the aorta. A mediastinal biopsy revealed fibrous connective tissue with small-vessel hyperplasia and acute-chronic inflammatory cell infiltration. The initial diagnosis was retroperitoneal fibrosis (RPF), and hormonal and tamoxifen treatments were administered. The patient presented with oliguria, eyelid edema and fever four years later. A repeat CT revealed an increase in the extent of tissue infiltration and pericardial effusion compared with the previous CT. Subsequent cardiac magnetic resonance imaging revealed massive thickening in the form of fibrotic tissue infiltrating the heart and surrounding thoracic and abdominal aorta. Single photon emission CT revealed multiple areas of increased bone metabolism, particularly symmetrical involvement of the long bones of both lower extremities. A biopsy of the perirenal tissue revealed fibrous tissue and a small number of lymphocytes and macrophages [typical foamy histiocytes observed via x200 magnification and hematoxylin-eosin (HE) staining, no presence of xanthogranuloma or Touton giant cells]. After a comprehensive evaluation and ruling out other diseases, the diagnosis of ECD was determined. The prognosis of this disease is poor; early diagnosis is critical and requires accurate judgment by clinicians. Biopsies of all involved sites and refinement of genetic tests to guide treatment, if possible, are both necessary.

Mediastinal Rosai-Dorfman Disease with KRAS mutation case report and literature review

BACKGROUND

Rosai-Dorfman Disease (RDD) is a rare self-limiting histiocytosis, more prevalent in children and young adults. It typically manifests as painless bilateral massive cervical lymphadenopathy but may also extend to extra-nodal sites, with intrathoracic RDD noted in 2% of cases. Distinguishing mediastinal RDD from thymoma on imaging poses challenges, underscoring the reliance on pathological features and immunohistochemical staining for diagnosis.

CASE PRESENTATION

Patient, male, 33 years old, underwent lung a CT revealing an enlarged round soft tissue shadow in the anterior superior mediastinum, compared to a year ago. Surgical resection removed the entire mass, thymus, and part of the pericardium, confirming RDD on pathology. Genetic testing using second-generation testing technology identified a KRAS gene point mutation.

CONCLUSIONS

No established treatment protocol currently exists for this disease. However, as genetic mutation research progresses, a novel therapeutic avenue is emerging: targeted therapy integrated with surgical interventions.

Typical Bone Scintigraphy Presentation of Erdheim-Chester Disease in a Patient Diagnosed With IgG4-Related Disease

ABSTRACT

A 50-year-old woman presented a dry syndrome, joint pain, inflammatory syndrome, polyclonal hypergammaglobulinemia, and tubulointerstitial nephritis. Imaging studies (including FDG PET/CT) revealed infrarenal retroperitoneal fibrosis with periaortitis and hypermetabolic osteosclerotic lesions. Bone scintigraphy demonstrated intense uptake in the femoral, tibial, and radial regions, suggestive of non-Langerhans histiocytosis, specifically Erdheim-Chester disease. A bone biopsy confirmed the presence of IgG4-positive plasma cells but no histiocytes. The patient received corticosteroid therapy followed by rituximab, resulting in a complete response. This case suggests an atypical manifestation of bone lesions in IgG4-related disease, emphasizing the diagnostic challenge between IgG4-related disease and Erdheim-Chester disease.

Erdheim-Chester Disease Occult on Radiographs and CT but Visible on MRI and PET

BACKGROUND Erdheim-Chester disease (ECD) is a rare neoplasm of histiocytes that is characterized by prominent involvement of the long bones. Approximately 1500 cases have been reported since the disease was first described in 1930. The imaging appearance of ECD can be highly variable given the numerous systems it can affect. In this case report we discuss a patient whose ECD was occult on multiple imaging modalities. CASE REPORT We report the case of a 60-year-old woman who presented with sub-acute left knee and calf pain that led to an MRI. She was found to have innumerable marrow-replacing lesions in the axial and appendicular skeleton visualized on the initial MRI, as well as on an ¹⁸F-FDG PET/CT scan. The patient did not have extraosseous abnormal uptake on the PET/CT. Subsequently, a lesion from the left iliac bone was histologically confirmed as ECD on the basis of positive staining for CD68 and CD163 and negative staining for CD1a. Osseous lesions in ECD have a distinct imaging appearance and are typically detected by radiography and bone scintigraphy, among other modalities; however, the lesions in this case were unexpectedly absent from those studies. CONCLUSIONS If there is a high degree of suspicion for ECD, 18F-FDG PET/CT and/or MRI may be necessary for adequate visualization of bone lesions, given that those lesions can have an infiltrative nature that may be difficult to image with other anatomic imaging modalities. Use of 18F-FDG PET/CT and/or MRI may also lead to adequate guidance of confirmatory biopsy.

Erdheim-Chester Disease: Investigating the Correlation between Targeted Treatment Therapy and Disease Outcomes

A retrospective analysis of 20 adult patients with histopathological and clinical diagnoses of ECD was conducted at a single institution over a twenty-year period (2002-2022). Clinical responses were compared on the basis of treatments rendered, which included chemotherapy, immunotherapy, systemic corticosteroids, surgery and radiation, or targeted agents, referring to any small molecular inhibitors. Treatment response evaluation varied by the anatomic site(s) of disease, the extent of disease at diagnosis, and the imaging modality employed. In this analysis, patients were treated with a combination of targeted agents, myelosuppressive therapies, and radiation at various points in their disease courses. Of these, the most common treatment modality rendered was targeted therapy, employed in 11 of 20 patients. Partial responses or better were observed in 15 of 20 patients. Rates of stable disease trended towards being more frequent with targeted therapy versus conventional therapy but did not reach significance (p = 0.2967). Complete response rates trended towards being more common with conventional therapy than molecular (p = 0.5) but were equivocal overall. Trends of peripheral blood absolute monocytes with relation to disease activity were reviewed as recent literature implied that monocyte levels surrounding disease progression were of potential prognostic significance in histiocytic diseases. Amongst the patients who progressed at any point during their treatment course, absolute monocyte count (in K/µL) was identified at the closest available timepoint prior to or following disease progression and at the lowest value (nadir) following re-institution of therapy prior to any additional agent(s) being employed. There was no statistically significant difference in either of these monocyte values nor in disease outcomes with respect to treatments rendered within our cohort. However, our cohort consists of a heterogenous population of patients with ECD with data that highlights several trends over a longitudinal period, spanning the advent of targeted therapy. Significant differences are anticipated in ongoing analyses.

Cardiac mass as the primary diagnostic clue of Edheim-Chester disease

Key Clinical Message

We introduced one of the rare causes of intra-cardiac mass, that is, ECD and a new gene mutation (SLC29A3) that is probably related to this disease, and we noted the importance of using several diagnostic methods to rule out other intra-cardiac causes.

Abstract

Edheim-Chester disease is a rare histiocytosis affecting multiple organs. The infiltration of lipid-laden histiocytes characterizes the disease. Most patients experience bone involvement; over 50% of cases involve the cardiovascular system and other extra-osseous organs. In this case report, we present the case of a 42-year-old man who complained of shortness of breath and bone pain. During echocardiography, a large, homogenous, and fixed mass was found in the right atrium free wall. Computed tomography and cardiac magnetic resonance imaging revealed an infiltrative mass in the RA with atrioventricular groove involvement but coronary sinus encasement, right coronary artery, and superior vena cava encasement. Abdominal CT scans also reported aortic wall involvement and bilateral renal cortical and perirenal involvement. A kidney biopsy confirmed the infiltration of histiocytes and the diagnosis of ECD. The treatment was initiated for him, and his symptoms improved. In this case report, we express the importance of considering the rare causes of cardiac tumors.

Skeletal involvement in Erdheim-Chester disease: Multimodality imaging features and association with the BRAFV600E mutation

OBJECTIVE

The aim of this study was to characterize the distribution of skeletal involvement in Erdheim-Chester disease (ECD) by using radiography, computed tomography (CT), 18F-FDG positron emission tomography/computed tomography (PET/CT), and bone scans, as well as looking for associations with the BRAFV600E mutation.

MATERIAL AND METHODS

Prospective study of 50 consecutive patients with biopsy-confirmed ECD who had radiographs, CT, 18F-FDG PET/CT, and Tc-99m MDP bone scans. At least two experienced radiologists with expertise in the relevant imaging studies analyzed the images. Summary statistics were expressed as the frequency with percentages for categorical data. Fisher's exact test, as well as odds ratios (OR) with 95 % confidence intervals (CI), were used to link imaging findings to BRAFV600E mutation. The probability for co-occurrence of bone involvement at different locations was calculated and graphed as a heat map.

RESULTS

All 50 cases revealed skeletal involvement at different regions of the skeleton. The BRAFV600E mutation, which was found in 24 patients, was correlated with femoral and tibial involvement on 18F-FDG PET/CT and bone scan. The appearance of changes on the femoral, tibial, fibular, and humeral involvement showed correlation with each other based on heat maps of skeletal involvement on CT.

CONCLUSION

This study reports the distribution of skeletal involvement in a cohort of patients with ECD. CT is able to detect the majority of ECD skeletal involvement. Considering the complementary nature of information from different modalities, imaging of ECD skeletal involvement is optimized by using a multi-modality strategy.

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.

The role of 2-[18F]FDG PET/CT in Erdheim-Chester disease

OBJECTIVE

To analyze the body distribution of Erdheim-Chester disease (ECD) and determine the utility of 2-[18 F]FDG PET/CT compared to other imaging techniques. Additionally, to assess the aggressiveness and extent of the disease based on the presence/absence of the BRAFV600E mutation.

MATERIALS AND METHODS

The 2-[18F]FDG-PET/CT scans of all patients diagnosed with ECD between 2008 and 2021 were reviewed, including 19 patients. The affected territories were classified as detectable by PET/CT or detectable only by other imaging techniques (bone scintigraphy, contrast-enhanced CT, or MRI). Descriptive analysis and correlation of the BRAF mutation with the affected organs and maximum SUV were performed using the Student's t-test.

RESULTS

Out of the 19 patients (14 males; mean age 60.3 years), 11 had the BRAFV600E mutation. A total of 127 territories (64 organ-systems) affected were identified using different imaging modalities, of which 112 were detected by PET/CT, and an additional 15 territories were solely identified by cerebral and cardiac MRI. The presence of BRAFV600E mutation was associated with greater organ involvement (p < 0.05) without differences in SUVmax (p > 0.05).

CONCLUSION

2-[18F]FDG PET/CT is a highly effective diagnostic tool in patients with ECD, detecting the majority of affected territories. MRI was the only imaging modality with additional findings in territories showing high physiological uptake of 2-[18F]FDG (cerebral and cardiac). The presence of the BRAFV600E mutation correlated with a higher extent of the disease.

A rare case report of Erdheim-Chester disease with pericardial effusion, conduction abnormalities, and atrial infiltration

Background

Erdheim-Chester disease (ECD) is a rare multisystem disorder that primarily affects adults. It is characterized by the excessive production and accumulation of histiocytes, a type of white blood cell, within multiple tissues and organs, including the cardiovascular system. The infiltration of histiocytes can cause a range of cardiovascular symptoms, including pericardial effusion, myocardial infiltration, and heart failure, among others. Despite the potential severity of these cardiovascular manifestations, ECD is often misdiagnosed or underdiagnosed, leading to delays in appropriate treatment and poor outcomes for patients. As such, there is a pressing need for increased awareness and understanding of ECD's cardiovascular manifestations among clinicians and researchers. This article aims to highlight the importance of considering ECD as a potential underlying cause of cardiovascular complaints and to encourage further investigation into this uncommon but potentially life-threatening condition.

Case summary

A 63-year-old man presented as outpatient complaining of dyspnoea on exertion during the last 3 weeks (New York Heart Association functional class III). He had also experienced a left shoulder and bilateral knee pain over the last 6 months. The patient was found to have a massive pericardial effusion associated with ECD. While pericardial effusions can have various causes, including infection, cancer, and autoimmune disorders, ECD is one potential cause of this condition. Therefore, it is important for clinicians to consider ECD in the differential diagnosis of patients presenting with unexplained pericardial effusions, particularly in the context of other systemic symptoms suggestive of ECD. We discuss about this specific aetiology and the clinical management of this uncommon condition.

Discussion

Erdheim-Chester disease, a non-Langerhans cell histiocytosis, is a rare multisystem disorder. Diagnosis is challenging and should be suspected in the presence of a pericardial effusion with conduction abnormalities with indicators of a multisystem disease.

Cardiac Masses and Pseudomasses: An Overview about Diagnostic Imaging and Clinical Background

A cardiac lesion detected at ultrasonography might turn out to be a normal structure, a benign tumor or rarely a malignancy, and lesion characterization is very important to appropriately manage the lesion itself. The exact relationship of the mass with coronary arteries and the knowledge of possible concomitant coronary artery disease are necessary preoperative information. Moreover, the increasingly performed coronary CT angiography to evaluate non-invasively coronary artery disease leads to a rising number of incidental findings. Therefore, CT and MRI are frequently performed imaging modalities when echocardiography is deemed insufficient to evaluate a lesion. A brief comprehensive overview about diagnostic radiological imaging and the clinical background of cardiac masses and pseudomasses is reported.

Apparently isolated CNS involvement in Erdheim-Chester disease: Case report

We present the case of a 48-year-old-woman with apparently isolated central nervous system Erdheim-Chester disease characterized by brainstem involvement. Erdheim-Chester disease is extremely rare and multisystem impairment should always be sought in the suspicion of such pathology.

Erdheim-Chester Disease with Renal Mass Presentation: Report of the First Case From Palestine and a Review of the Literature

BACKGROUND Erdheim-Chester disease (ECD), a form of non-Langerhans-cell histiocytosis, is extremely rare. The mean age of individuals with ECD is in their 50s. Histiocytic infiltration of vital organ systems is a potential cause of substantial morbidity, which is associated with the multisystemic form of ECD. This report presents the first case of ECD with renal abnormalities in Palestine. CASE REPORT A 54-year-old woman with no medical or surgical history presented with 6 months of bilateral flank pain with no radiation or fever. A physical examination revealed only bilateral flank pain. Urine tests showed microhematuria. Laboratory test results showed increased serum creatinine levels (1.21 mg/dL) and microcytic anemia. A CT scan revealed significant multi-organ abnormalities, including renal abnormalities with a hairy kidney sign, pericardial effusion, and an osteolytic lesion of the spine. The hairy kidney sign is pathognomonic for ECD, so the renal mass was biopsied to confirm the diagnosis. The biopsy showed foamy histiocytes, lymphocytes, and plasma cells. Foamy histiocytes were CD68-positive and negative for S100, CD1a, and HMB45. PAx5 and CD3 immunostaining showed T-predominant B-lymphocyte mixtures. CONCLUSIONS In the setting of systemic symptoms and imaging abnormalities such as presence of the hairy kidney sign, pericardial effusion, and osteolytic lesion of the spine, it is necessary to examine the possibility of ECD and proceed with a biopsy for confirmation. This is the first case in Palestine to be reported and the second case worldwide with a renal mass as an atypical presentation.

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.