Erdheim-Chester disease (ECD) is a systemic histiocytosis that can involve several organs, with severity ranging from occult to life-threatening. The disease was first described by William Chester in 1930 after working with the Austrian pathologist Jakob Erdheim. Even today, a correct diagnosis of ECD often takes years, given the rarity and variable manifestations of ECD. We present a case of a 63-year-old female presenting with multiple brain lesions, sent for fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography to find primary, and it showed hypermetabolic right occipital brain lesion, right orbital lesion, and soft tissue around the arch of the aorta (coated aorta), and final histopathology of the brain lesion confirmed histiocytosis ECD.

UNASSIGNED: 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.
UNASSIGNED: 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.
UNASSIGNED: 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.

Erdheim-Chester Disease (ECD) is a rare non-Langerhans form of systemic histiocytosis of unknown etiology with multiple organ involvement. It most commonly affects the long bones, lungs, heart, retroperitoneum, eyes, and kidneys and less commonly the brain and spinal cord. Although there are very few cases of supratentorial ECD mimicking intracranial meningioma reported in literature, to the best of our knowledge, there are no reports on ECD mimicking infratentorial pontocerebellar angle meningioma. The present study reports a case of ECD mimicking pontocerebellar angle meningioma. This study aimed to emphasize the importance of systemic evaluation using a multidisciplinary approach as well as the need for considering ECD as a differential diagnosis of xanthomatous meningioma.

(1) Introduction: Erdheim-Chester disease (ECD) is a life-threatening condition and often a diagnostic challenge. It has recently been classified as a hematopoietic tumour, and the cases of ECD reported in the literature has dramatically increased during the last 15 years. (2) Methods: We describe the case of a 57-year-old male patient with severe gynecomastia, with a detailed description of his diagnostic iter and consequent surgical operation. We provide the first systematic review of the literature of breast involvement in ECD, following PRISMA guidelines, including 13 studies and 16 patients. (3) Results: Our report resulted to be the first case of gynecomastia as a single clinical and imaging feature of ECD described in English literature. A total of 81.3% of patients included were female. Among them, 76.9% had unilateral and nodular presentation, while male patients presented bilateral heterogeneous breast enlargement. Globally, 87.5% expressed breast alterations as their first manifestations of ECD. Only 50% presented skeletal involvement. (4) Conclusion: The reported case represents a unique addition to the literature. We found two different patterns in ECD-related breast involvement between male and female patients, an unusual M/F ratio, and a lower rate of bone involvement. Breast involvement is frequently the first clinical feature; therefore, breast caregivers should be aware of this dangerous and most likely underestimated condition.

Erdheim-Chester disease is characterized by the infiltration of foamy histiocytes in tissues. Lesional tissue biopsy is recommended to confirm diagnosis and establish the BRAF mutational status. A 52-year-old man presented to our hospital with hydronephrosis. Computed tomography showed enhancement of soft shadows around the left renal pelvis transition area and the aorta. He was treated with prednisolone 0.2 mg/kg for 1 year; however, no improvement was observed. 18Fluorodeoxyglucose-positron emission tomography/computed tomography revealed increased fluorodeoxyglucose uptake in various body parts, including the maxillary sinuses, indicative of Erdheim-Chester disease. He refused further examination, and the maxillary sinus lesions were treated with antibiotics and intranasal steroids, but no improvement was observed. Two years later, he underwent biopsy with endoscopic sinus surgery of the maxillary sinus, which showed the highest increase in fluorodeoxyglucose uptake on repeat 18fluorodeoxyglucose-positron emission tomography/computed tomography. Endoscopic findings showed only nonspecific inflammatory findings, but pathological findings revealed the proliferation of cells with abundant foamy cytoplasms. Sufficient tumor volume was available to perform PCR for BRAF V600E mutation analysis, which was positive and resulted in a diagnosis of Erdheim-Chester disease with the BRAF V600E mutation. This is the first case of a patient with Erdheim-Chester disease with the BRAF V600E mutation identified in a sinus lesion. Endoscopic sinus surgery biopsy of the paranasal sinuses was considered to contribute to the histological and genetic diagnosis of Erdheim-Chester disease, particularly following the notable increase in fluorodeoxyglucose uptake.

Neurological involvement is relatively common in Erdheim-Chester disease (ECD), a rare clonal disorder of histiocytic myeloid precursors characterized by multisystem involvement. In ECD patients, neurological symptoms can occur either at onset or during the disease course and may lead to various degrees of neurological disability or affect patients\' life expectancy. The clinical neurological presentation of ECD often consists of cerebellar symptoms, showing either a subacute or progressive course. In this latter case, patients manifest with a slowly progressive cerebellar ataxia, variably associated with other non-specific neurological signs, infratentorial leukoencephalopathy, and cerebellar atrophy, possibly mimicking either adult-onset degenerative or immune-mediated ataxia. In such cases, diagnosis of ECD may be particularly challenging, yet some peculiar features are helpful to address it. Here, we retrospectively describe four novel ECD patients, all manifesting cerebellar symptoms at onset. In two cases, slow disease progression and associated brain MRI features simulated a degenerative cerebellar ataxia. Three patients received a definite diagnosis of histiocytosis, whereas one case lacked histology confirmation, although clinical diagnostic features were strongly suggestive. Our findings regarding existing literature data focused on neurological ECD will be also discussed to highlight those diagnostic clues helpful to address diagnosis.

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.

Erdheim-Chester disease is a rare histiocytosis characterized by iconic features associated with compatible histology. Most patients have somatic mutations in the MAP-kinase pathway gene, and the mutations occur in CD14+ monocytes. Differentiation of the myeloid lineage plays a central role in the pathogenesis of histiocytosis. Monocytes are myeloid-derived white blood cells, divided into three subsets, but only the CD14++CD16- \"classical monocyte\" can differentiate into dendritic cells and tissue macrophages. Since most mutations occur in CD14+ cells and since ECD patients have a particular monocytic phenotype resembling CMML, we studied the correlation between disease activity and monocytic subset distribution during the course of a severe vascular form of ECD requiring liver transplantation. During early follow-up, increased CD14++CD16- \"classical monocyte\" associated with decreased CD14lowCD16++ \"non-classical monocyte\" correlated with disease activity. Further studies are needed to confirm the use of monocyte as a marker of disease activity in patients with ECD.

UNASSIGNED: Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis that can affect the bones, heart, lungs, brain, and other organs. Cardiovascular involvement is common in ECD and is associated with a poor prognosis. Here, we report a case of ECD presenting as an intracardiac mass and pericardial effusion confirmed by biopsy with sternotomy.
UNASSIGNED: A 54-year-old man was admitted because of dyspnoea. He was previously diagnosed with bilateral hydronephrosis and retroperitoneal fibrosis. Echocardiography revealed a large amount of pericardial effusion and echogenic mass on the right atrial (RA) side and atrioventricular (AV) groove. Cardiac magnetic resonance imaging and positron emission tomography-computed tomography (CT) revealed infiltrative mass-like lesions in the RA and AV groove. Pericardial window formation and pericardial biopsy were performed, and the pathologic results showed only pericardial fibrosis with no specific findings. Bone scan revealed increased uptake in the long bones. Considering the high probability of ECD based on the patient\'s manifestations and the imaging findings, we performed a cardiac biopsy with median sternotomy despite initial insufficient pathologic results in the pericardial biopsy. The surgical findings included multiple irregular and firm masses on the cardiac wall and large vessels; after obtaining a large amount of suspicious mass, ECD accompanied with CD68 (+) and BRAF V600E mutation was confirmed.
UNASSIGNED: Erdheim-Chester disease can be associated with various forms of cardiovascular involvement. Considering the multi-systemic manifestations and difficulty in identifying this rare disease, a comprehensive and meticulous diagnostic work-up is crucial.

A 70-year-old male presented with orbital masses affecting the muscular cone. His past medical history was notable for diabetes mellitus, ischemic cardiopathy, sleep-apnea syndrome, and multiple serous effusions. The first biopsy specimen of affected orbital tissue revealed fibrohistiocytic infiltration resembling xanthogranuloma or Erdheim-Chester disease (ECD). An ulterior biopsy of affected orbital tissue showed lymphocyte emperipolesis with immunopositivity for CD68 and S100 but negative staining for CD1a marker, strongly suggesting Rosai-Dorfman disease (RDD). Afterward, pericardium and peritoneal effusions resulted in constrictive pericarditis and retroperitoneal fibrosis, respectively. The absence of distinctive clinical features made the diagnosis especially challenging. Attempts to control the disease using corticosteroids, radiation, orbital surgery, and interferon were unsuccessful. Aggressive treatments such as chemotherapy were not considered appropriate due to the general deterioration of our patient. Although the possibility of two concurrent diseases (e.g., systemic ECD and orbital RDD) cannot be discarded, we interpreted the orbital findings as likely due to RDD, and the entire condition of our patient as an extranodal RDD with atypical clinicopathological findings and outcome.