Erdheim-Chester disease: CT findings of thoracic involvement

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.

Paradoxical coronary embolism in Erdheim-Chester disease: invasive assessment and multidisciplinary management

We report a case of non-ST elevation myocardial infarction in a 36-year-old man with Erdheim-Chester disease (ECD). Multimodality assessment revealed acute coronary thrombus with simultaneous recurrent pulmonary embolism in spite of compliance with a direct oral anticoagulant. Prior case reports of acute myocardial infarction in this population have not outlined the role of catheter based intravascular assessment and treatment in this rare clinical entity.

Coronary Artery Vasculitis and Encasement: Multimodality Imaging Findings and Mimics

Coronary artery vasculitis (CAV) and coronary artery encasement are rarely diagnosed conditions that are important diagnostic considerations, particularly in patients with acute coronary syndrome without traditional cardiovascular risk factors or systemic illness. Vasculitis refers to inflammation of the blood vessel walls, which can be primary or secondary. This process should be distinguished from neoplastic involvement of the coronary arteries, termed coronary artery encasement. Prospective diagnosis of these diseases is challenging, often requiring multidisciplinary workup with careful attention to clinical presentation and multiorgan findings. While CAV and coronary artery encasement can be indistinguishable at coronary CT angiography, certain imaging features help order the differential diagnosis. CAV should be considered when there is smooth wall thickening that is circumferential and/or continuous. A diagnosis of coronary artery encasement is favored when there is irregular or nodular wall thickening that is eccentric to the vessel lumen. Epicardial fat stranding may also appear more extensive compared with CAV. Potential mimics of CAV include atherosclerosis, acute plaque rupture, coronary artery aneurysm, and spontaneous coronary artery dissection. Detection and diagnosis of CAV may help avoid complications related to accelerated atherosclerosis and infarction. Radiologists should be familiar with the range of pathologic conditions that can affect the coronary arteries beyond atherosclerosis as they may be the first to raise such diagnostic possibilities, guiding next steps in patient workup and management. ©RSNA, 2024 Supplemental material is available for this article.

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.

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.

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.

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.

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 recurrent pleuropneumonia revealing Erdheim-Chester Disease

Erdheim-Chester disease (ECD) is a rare form of L group histiocytosis, accounting for up to 1500 cases to date worldwide, which mainly affects men between their 5th and 7th decade of life. The most frequent manifestations are bone involvement, perirenal infiltration with an evocating appearance of "hairy kidneys", and a "coated aorta" aspect. Lung involvement in ECD is less common and includes pleural infiltration and interstitial lung disease. Herein, we report the case of a 76-year-old woman with recurrent pleuropneumonia revealing ECD.

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.

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.

Pulmonary manifestations of Erdheim-Chester disease: clinical characteristics, outcomes and comparison with Langerhans cell histiocytosis

Erdheim-Chester disease (ECD) is a rare form of non-Langerhans cell histiocytosis that typically affects many organs, including the lung and pleura. However, there are few studies concerning pulmonary involvement in ECD patients, as well as the difference of pulmonary involvement between ECD and Langerhans cell histiocytosis (LCH). We performed a retrospective study of 54 ECD patients, and compared the pulmonary manifestations with those of adult LCH patients in our centre. The median age of diagnosis of the 54 ECD patients was 48 years (range 9-66 years). Chest computed tomography (CT) scans revealed lung involvement in 49 (91%) patients and pleural involvement in 34 (63%). Thirty-three (61%) patients had interstitial lung disease (ILD) with varying degrees of interlobular septal thickening, micronodules, and ground-glass opacities. ECD and LCH patients with pulmonary involvement showed significant differences in smoking status (P < 0·001), respiratory symptoms (P = 0·001) such as cough and pneumothorax (P < 0·001), and radiological findings, including cysts (P < 0·001), opacities (P < 0·001), and pleural thickening (P < 0·001). With a median follow-up duration of 24 months (range, 1-84 months), the estimated three-year overall survival (OS) of this entire ECD cohort was 90·2%. Patients with ILD tended to have worse progression-free survival (PFS) than those with no ILD (P = 0·29).

Erdheim-Chester disease: a comprehensive review from the ophthalmologic perspective

Erdheim-Chester disease (ECD) is a rare clonal histiocytic neoplasm with less than 1200 documented cases to date. The disease is life-threatening and difficult to recognize, although increasing awareness as well as the integration of clinical, imaging, pathology information , and genetic studies have led to a recent exponential increase in new reported cases. ECD affects multiple organs and systems, including skeletal, neurologic, and cardiovascular. Pulmonary, retroperitoneal, and cutaneous lesions have also been reported in various combinations. Until the discovery that more than half of ECD patients harbor the BRAF-V600E mutation or other mutations in the mitogen-activated protein kinase (MAPK) and RAS pathways, Interferon-a was the first-line treatment. Nowadays BRAF and MEK-inhibitors targeted therapies are the mainstay of treatment. Ophthalmologic involvement occurs in 25% -30% of ECD cases, usually in the form of orbital involvement presenting with exophthalmos and ophthalmoplegia. Other ophthalmologic manifestations include palpebral xanthelasmas, anterior uveitis and vitritis, optic disk edema, choroidal infiltration, recurrent serous retinal detachment, retinal drusen-like deposits and retinal pigment epithelial changes. ECD patients can also present with ocular symptoms as a result of adverse effects of the treatment regimens. In some cases with smoldering or protean symptoms, the emergence of eye manifestations triggered the diagnosis. Ophthalmologists have to be aware of the disease, recognize the constellation of ECD symptoms, and contribute to the diagnosis, treatment, and follow-up of ECD patients.

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.

Beyond Giant Cell Arteritis and Takayasu's Arteritis: Secondary Large Vessel Vasculitis and Vasculitis Mimickers

PURPOSE OF REVIEW

To provide an overview of mimickers of large vessel vasculitis (LVV), by the main presenting manifestation, i.e., systemic, vascular, and cranial manifestations.

RECENT FINDINGS

The main differential diagnoses in patients with giant cell arteritis (GCA) and Takayasu arteritis (TAK) presenting with systemic manifestations (i.e., fever, anorexia, weight loss, night sweats, arthralgia/myalgia, and/or increased inflammatory indexes) are neoplastic, infectious, or other inflammatory conditions. In patients with vascular manifestations (such as peripheral ischemia, vascular stenoses, or aneurysms), atherosclerosis and non-inflammatory vascular diseases should be excluded. In those presenting with predominant cranial symptoms (i.e., temporal headache, jaw claudication, scalp tenderness, transient or permanent vision loss), other causes of headache, cerebrovascular accidents, optic neuropathy, and neuromuscular syndromes need to be considered. The diagnosis of LVV maybe challenging, especially when patients present with atypical or incomplete clinical forms. In these cases, a multidisciplinary approach is strongly recommended.

Erdheim-Chester disease

Erdheim-Chester disease (ECD) is characterized by the infiltration of tissues by foamy CD68+CD1a- histiocytes, with 1500 known cases since 1930. Mutations activating the MAPK pathway are found in more than 80% of patients with ECD, mainly the BRAFV600E activating mutation in 57% to 70% of cases, followed by MAP2K1 in close to 20%. The discovery of BRAF mutations and of other MAP kinase pathway alterations, as well as the co-occurrence of ECD with LCH in 15% of patients with ECD, led to the 2016 revision of the classification of histiocytoses in which LCH and ECD belong to the "L" group. Both conditions are considered inflammatory myeloid neoplasms. Ten percent of ECD cases are associated with myeloproliferative neoplasms and/or myelodysplastic syndromes. Some of the most striking signs of ECD are the long bone involvement (80%-95%), as well as the hairy kidney appearance on computed tomography scan (63%), the coated aorta (40%), and the right atrium pseudo-tumoral infiltration (36%). Central nervous system involvement is a strong prognostic factor and independent predictor of death. Interferon-α seems to be the best initial treatment of ECD. Since 2012, more than 200 patients worldwide with multisystem or refractory ECD have benefitted from highly effective therapy with BRAF and MEK inhibitors. Targeted therapies have an overall, robust, and reproducible efficacy in ECD, with no acquired resistance to date, but their use may be best reserved for the most severe manifestations of the disease, as they may be associated with serious adverse effects and as-yet-unknown long-term consequences.

Imaging features and differential diagnoses of non-neoplastic diffuse mediastinal diseases

Acute or chronic non-neoplastic diffuse mediastinal diseases have multiple causes, degrees of severity, and a wide range of management. Some situations require emergency care while others do not need specific treatment. Although the diagnosis may be suspected on chest X-ray, it is mainly based on CT. A delayed recognition is not uncommonly observed. Some findings may prompt the radiologist to look for specific associated injuries or lesions.

This pictorial review will successively describe the various non-neoplastic causes of diffuse mediastinal diseases with their typical findings and major differentials.

First, pneumomediastinum that can be provoked by extra- or intra-thoracic triggers requires the knowledge of patient’s history or recent occurrences. Absence of any usual etiological factor should raise suspicion of cocaine inhalation in young individuals.

Next, acute mediastinitis may be related to post-operative complications, esophageal perforation, or contiguous spread of odontogenic or retropharyngeal infections. The former diagnosis is not an easy task in the early stage, owing to the similarities of imaging findings with those of normal post-operative appearance during the first 2–3 weeks.

Finally, fibrosing mediastinitis that is linked to an excessive fibrotic reaction in the mediastinum with variable compromise of mediastinal structures, in particular vascular and airway ones. Differential diagnosis includes tumoral and inflammatory infiltrations of the mediastinum.

Erdheim-Chester disease progression from miliary pulmonary nodules to large tumours

Erdheim-Chester disease (ECD), a rare form of non-Langerhans cell histiocytosis, affects long bones, the retroperitoneal region, and the central nervous, cardiovascular, and pulmonary systems. Most patients with ECD show interlobular septal thickening, centrilobular micronodules, and ground glass opacities on chest computed tomography (CT). We encountered a 66-year-old man with ECD who presented at first visit with randomly distributed multiple pulmonary nodules and who then developed large tumour shadows, observed on chest CT. To our knowledge, this random distribution pattern of multiple pulmonary nodules has not previously been reported.

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.

Thyroid Rosai-Dorfman disease with infiltration of IgG4-bearing plasma cells associated with multiple small pulmonary cysts

Background

Rosai-Dorfman disease (RDD) is a rare histiocytosis which involves principally lymph nodes. Thyroid involvement in RDD is a very rare situation, and lung involvement is even rarer.

Case presentation

We report the case of a 46-year-old woman presenting a painless mass in the right side of the neck and subacute dyspnoea. Computerised tomography (CT) scans of the neck and thorax showed a large thyroid mass causing tracheal stenosis and multiple cystic lesions in both lungs. Subtotal thyroidectomy with a tracheal segment resection and histological analysis confirmed the diagnosis of nodal and extranodal (thyroid, tracheal and probably lung) Rosai-Dorfman disease (RDD) with the presence of increased numbers of IgG4-bearing plasma cells. Clinical, functional and radiological follow up 4 years after surgery without medical treatment did not show any disease progression.

Conclusions

This case report indicates a benign course of nodal RDD with thyroid and tracheal infiltration following surgical resection, association of typical histological signs of RDD (emperipolesis) with IgG4-related disease features, and that lung cysts might be a manifestation of RDD.

Arterial involvement in Erdheim-Chester disease: A retrospective cohort study

Erdheim-Chester disease (ECD) is a rare histiocytosis of the "L" (Langerhans) group with multisystem involvement that can affect the large and medium-sized arteries mimicking vasculitis. Aortic involvement is common but the frequency and outcome of aortic branch vessel abnormalities are less well described.Patients with ECD were retrospectively identified. Images containing information of arterial involvement within 6 months of diagnosis were considered baseline and compared to last follow-up studies. Two physicians independently reviewed the studies to evaluate for presence of abnormalities attributable to ECD. Age and sex-adjusted logistic regression models were used to examine associations between patient characteristics and vessel involvement at baseline.Among a cohort of 64 patients with ECD, 63 had baseline imaging of vascular structures. ECD involvement of at least 1 segment of the aorta was observed in 56%. Abnormalities were also observed in aortic arch branches (26%), visceral branch arteries (40%), iliofemoral arteries (31%), coronary (5%), and pulmonary (3%) arteries. Perinephric fibrosis was strongly associated with the identification of abnormalities in the thoracic aorta (OR 4.92 [1.54, 15.75]; P = .007), abdominal aorta (OR 7.57 [2.28, 25.07]; P = .001) and visceral branch arteries (OR 6.05 [1.52, 24.03]; P = .01) but not pelvic/lower extremity arteries. Complete normalization of arterial abnormalities at follow-up was only observed in 9% or less of arterial segments involved at baseline.Aortic and aortic branch vessel abnormalities are frequently observed in patients with ECD and are often asymptomatic. Partial and/or complete resolution of arterial findings is uncommon.

Imaging of Histiocytosis in the Era of Genomic Medicine

Histiocytosis describes a group of diseases that have long been considered enigmatic in the history of medicine. Recently, novel genomic analyses have identified somatic oncogenic driver mutations responsible for the pathogenesis of these entities. These discoveries have led to the recharacterization of histiocytoses as neoplastic diseases and have opened a new era of precision medicine approaches for treatment. The histiocytic disorders demonstrate a variety of imaging manifestations involving multiple organ systems, and radiologists play a major role in diagnosis and monitoring. An up-to-date knowledge of the novel genomic discoveries and their implications is essential for radiologists to understand the new approaches to treating histiocytic disorders and to contribute as key members of the multidisciplinary treatment team. This article provides a cutting-edge review of the novel concepts in histiocytosis, with a focus on recent genomic discoveries and precision medicine approaches to treating the disease, and describes imaging manifestations with correlative histologic and genomic findings, with an emphasis on adult-onset cases and uncommon subtypes. ^©RSNA, 2018.

Clinical and Histopathologic Features of Interstitial Lung Disease in Erdheim⁻Chester Disease

Limited information is available regarding interstitial lung disease (ILD) in Erdheim⁻Chester disease (ECD), a rare multisystemic non-Langerhans cell histiocytosis. Sixty-two biopsy-confirmed ECD patients were divided into those with no ILD (19.5%), minimal ILD (32%), mild ILD (29%), and moderate/severe ILD (19.5%), based on computed tomography (CT) findings. Dyspnea affected at least half of the patients with mild or moderate/severe ILD. Diffusion capacity was significantly reduced in ECD patients with minimal ILD. Disease severity was inversely correlated with pulmonary function measurements; no correlation with BRAF V600E mutation status was seen. Reticulations and ground-glass opacities were the predominant findings on CT images. Automated CT scores were significantly higher in patients with moderate/severe ILD, compared to those in other groups. Immunostaining of lung biopsies was consistent with ECD. Histopathology findings included subpleural and septal fibrosis, with areas of interspersed normal lung, diffuse interstitial fibrosis, histiocytes with foamy cytoplasm embedded in fibrosis, lymphoid aggregates, and focal type II alveolar cell hyperplasia. In conclusion, ILD of varying severity may affect a high proportion of ECD patients. Histopathology features of ILD in ECD can mimic interstitial fibrosis patterns observed in idiopathic ILD.

Thoracic involvement in Erdheim-Chester disease: computed tomography imaging findings and their association with the BRAFV600E mutation

OBJECTIVES

To investigate the computed tomography (CT) thoracic findings in Erdheim-Chester disease (ECD) and evaluate the association of these findings with the BRAF^V600E mutation.

METHODS

This was a prospective study of patients with ECD (n=61, men=46) who underwent thoracic CT imaging. CT examinations were independently interpreted by two experienced radiologists. Association of imaging findings with BRAF^V600E was achieved via the Chi-square or Fisher's exact test and odds ratios (OR) with 95% confidence intervals (CI), as appropriate.

RESULTS

Fifty-five ECD patients (90%) showed pulmonary findings, which included interlobular septal thickening (69%), pulmonary nodules (62%), airway thickening (13%) and ground glass opacities (36%). Pulmonary nodules were classified by the pattern of distribution: subpleural regions (36%), lung parenchyma (13%) and both regions (13%). Pleural and mediastinal involvement were present in 15% and 62% of cases, respectively. The most common mediastinal finding was sheathing of the right coronary artery (34%), followed by sheathing of the thoracic aorta (30%). The BRAF^V600E mutation, positive in 31 patients, was associated with the frequency of sheathing of the coronary arteries (p = 0.01).

CONCLUSIONS

Of the thoracic findings reported in this study, we found a statistically significant positive association between the BRAF^V600E mutation and presence of coronary artery sheathing.

KEY POINTS

• To assess the degree of thoracic involvement in ECD with CT. • BRAF ^V600E mutation has a high association with right coronary artery sheathing. • BRAF ^V600E genetic testing detects patients at high risk of developing RCA sheathing.

Isolated pulmonary involvement in Erdheim-Chester disease

Erdheim–Chester disease is a rare non-Langerhans cell histiocytic disorder. It is primarily a disease of the long bones. Pulmonary involvement in systemic disease is detected in about half the reported cases. Isolated lung involvement is extremely rare with no clear recommendations for treatment. A 52-year-old caucasian male was evaluated for 1.9 cm × 1.6 cm spiculated nodule in the right upper lobe. Pulmonary function testing and bronchoscopy with endobronchial ultrasound, transbronchial biopsy, and microbiology were inconclusive. Positron emission tomography–computed tomography (PET-CT) was significant for the avidity in same lung nodule along with mediastinal and hilar adenopathy but no bone involvement. Wedge resection with histopathology and immunohistochemistry reported a fibrohistiocytic infiltrate in bronchovascular distribution which was positive for CD68 and negative for CD1A, S100, and BRAF V600E mutation. Magnetic resonance imaging brain ruled out central nervous system involvement. The rarity of the condition along with the complex pathology makes it difficult to diagnose and hence intervene appropriately.

Erdheim-Chester disease, moving away from the orphan diseases: A case report

With approximately 750 cases reported, Erdheim-Chester disease is an exceedingly rare histiocyte cell disorder. Affected sites typically include long bones, large vessels and central nervous system. However, cutaneous and pulmonary involvement can also occur. The diagnosis is ascertained by identification of foamy histiocytes positive for CD68, CD163, and factor XIIIa on immunoperoxidase staining. Recently published literature have described an association between Erdheim-Chester disease and BRAF V600E mutation. This finding prompted the investigation of therapeutic possibilities with BRAF inhibitors, successful agents against other BRAF mutation-positive diseases. Vemurafenib, a BRAF kinase inhibitor, has been shown to be effective in BRAF V600E mutation-positive malignancies, such as NSCLC and melanoma, as well as in several case reports of Erdheim-Chester disease. We report a case of Erdheim-Chester disease diagnosed at our institution, treated with vemurafenib.

Diagnostic Approach to Advanced Fibrotic Interstitial Lung Disease: Bringing Together Clinical, Radiologic, and Histologic Clues

Context.—

Idiopathic pulmonary fibrosis (IPF) is a distinctive clinicopathologic entity and the most common form of progressive diffuse lung scarring in older adults. Idiopathic pulmonary fibrosis manifests histopathologically as the usual interstitial pneumonia pattern. The usual interstitial pneumonia pattern is distinguished by geographically and temporally heterogeneous fibrosis that is peripherally accentuated, often with honeycombing and traction bronchiectasis. Idiopathic pulmonary fibrosis is not the only disease that leads to end-stage lung fibrosis, however, and several other entities may also cause advanced fibrosis. Surgical lung biopsies often present a diagnostic dilemma when they show clear evidence of advanced fibrosis, but the clinical, imaging, and/or histopathologic subcharacteristics suggest something other than IPF.

Objective.—

To address this dilemma, we review several other fibrotic lung diseases, including connective tissue disease–associated interstitial lung disease, chronic hypersensitivity pneumonitis, advanced pulmonary Langerhans cell histiocytosis, end-stage pulmonary sarcoidosis, Erdheim-Chester disease, Hermansky-Pudlak syndrome, and others, detailing their clinical, radiologic, and histopathologic attributes and emphasizing similarities to and differences from IPF.

Data Sources.—

Data sources comprised published peer-reviewed literature and personal experience of the authors.

Conclusions.—

Often, clues in the lung biopsy may offer the first suggestion of a fibrotic lung disease other than IPF, and accurate classification is important for prognosis, treatment, and the development of future therapies.

Cardiothoracic manifestations of primary histiocytoses

The objectives of this article were: (1) to review common and rare manifestations of systemic and pulmonary Langerhans cell histiocytosis, Rosai-Dorfman disease, Erdheim-Chester disease and juvenile xanthogranuloma; (2) to provide the reader with important pathologic, epidemiologic and clinical features of these diseases. The histiocytoses are a diverse group of diseases which typically manifest with multiorgan involvement. Understanding the pathologic, epidemiologic and clinical features of these entities can help the radiologist suggest an accurate diagnosis of histiocytosis when typical imaging features are encountered.

The 2015 World Health Organization Classification of Lung Tumors: Impact of Genetic, Clinical and Radiologic Advances Since the 2004 Classification

The 2015 World Health Organization (WHO) Classification of Tumors of the Lung, Pleura, Thymus and Heart has just been published with numerous important changes from the 2004 WHO classification. The most significant changes in this edition involve (1) use of immunohistochemistry throughout the classification, (2) a new emphasis on genetic studies, in particular, integration of molecular testing to help personalize treatment strategies for advanced lung cancer patients, (3) a new classification for small biopsies and cytology similar to that proposed in the 2011 Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification, (4) a completely different approach to lung adenocarcinoma as proposed by the 2011 Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification, (5) restricting the diagnosis of large cell carcinoma only to resected tumors that lack any clear morphologic or immunohistochemical differentiation with reclassification of the remaining former large cell carcinoma subtypes into different categories, (6) reclassifying squamous cell carcinomas into keratinizing, nonkeratinizing, and basaloid subtypes with the nonkeratinizing tumors requiring immunohistochemistry proof of squamous differentiation, (7) grouping of neuroendocrine tumors together in one category, (8) adding NUT carcinoma, (9) changing the term sclerosing hemangioma to sclerosing pneumocytoma, (10) changing the name hamartoma to "pulmonary hamartoma," (11) creating a group of PEComatous tumors that include (a) lymphangioleiomyomatosis, (b) PEComa, benign (with clear cell tumor as a variant) and

[Erdheim-Chester disease (ECD), an inflammatory myeloid neoplasia]

In a compatible clinico-radiological setting, the diagnosis of Erdheim-Chester disease (ECD) involves the analysis of histiocytes in tissue biopsies: they are typically foamy and CD68+ CD1a, whereas in Langerhans cell histiocytosis (LCH) they are CD68+ CD1a+. Overlap forms of histiocytoses are frequent. Technetium bone scintigraphy showing nearly constant tracer uptake by the long bones is highly suggestive of ECD and a 'hairy kidney' appearance on abdominal CT scan is observed in more than half ECD cases. CNS involvement is a strong prognostic factor and an independent predictor of death in cases of ECD. Optimal initial therapy for ECD appears to be administration of IFN-α (and/or pegylated IFN-α) and prolonged treatment significantly improves survival; however, tolerance may be poor. Best alternative therapies are anakinra, mainly effective for mild forms of the disease, infliximab, and sirolimus. Cases of ECD present with strong systemic immune activation, involving IFN-α, IL-1/IL1-RA, IL-6, IL-12, and MCP-1, consistent with the systemic immune Th-1-oriented disturbance associated with the disease. Between 57 and 75 % of ECD patients carry the BRAF^V600E mutation, an activating mutation of the proto-oncogene BRAF. More than 50 cases harboring BRAF mutation and with severe multisystemic and refractory ECD (sometimes associated with LCH) have been treated worldwide with vemurafenib, a BRAF inhibitor that proved to be very beneficial. Other recurrent mutations of the MAPK (NRAS, MAP2K1) and PIK3 pathways (PIK3CA) have been found among ECD patients. As recurrent mutations in the MAPK pathway are found in ECD and LCH on a background of chronic inflammation, we believe that both conditions should be redefined as an inflammatory myeloid neoplasia.

Histiocytic disorders of the chest: imaging findings

Histiocytic disorders of the chest comprise a broad spectrum of diseases. The lungs may be involved in isolation or as part of systemic disease. Some of these disorders are primary and have unknown etiology, and others result from a histiocytic response to a known cause. Among primary histiocytic disorders, pulmonary Langerhans cell histiocytosis (PLCH) is the most common; others include Erdheim-Chester disease and Rosai-Dorfman disease. Adult PLCH occurs almost exclusively in adults aged 20-40 years who smoke. Pediatric PLCH is extremely rare and typically occurs as part of multisystemic disease. Erdheim-Chester disease affects middle-aged and older adults; thoracic involvement usually occurs as part of systemic disease. Rosai-Dorfman disease affects children and young adults and manifests as painless cervical lymphadenopathy. Examples of secondary histiocytic disorders are storage diseases such as Gaucher disease, Niemann-Pick disease, and Fabry disease; pneumoconiosis such as silicosis and coal workers' pneumoconiosis; and infections such as Whipple disease and malakoplakia. These disorders are characterized at histopathologic examination on the basis of infiltration of alveoli or the pulmonary interstitium by histiocytes, which are a group of cells that includes macrophages and dendritic cells. Dendritic cells are a heterogeneous group of nonphagocytic antigen-presenting immune cells. Immunohistochemical markers help to distinguish among various primary histiocytic disorders. Characteristic radiologic findings in the appropriate clinical context may obviate biopsy to establish a correct diagnosis. However, in the absence of these findings, integration of clinical, pathologic, and radiologic features is required to establish a diagnosis.

Case 224: Cardiac Involvement in Erdheim-Chester Disease

History A 61-year-old man with no relevant medical history was admitted to the emergency department with symptoms of congestive heart failure and a 1-week history of chest pain, progressive dyspnea, abdominal swelling, bipedal edema, and anorexia. Laboratory test results, including complete blood count and electrolyte, creatinine, creatine phosphokinase, and troponin T levels were normal. Electrocardiographic findings were unremarkable. Initial chest radiography showed an enlarged heart with bilateral pleural effusion. Transthoracic echocardiography revealed an irregular right atrial mass and moderate to severe pericardial effusion. The patient subsequently underwent computed tomography (CT) of the chest, abdomen, and pelvis followed by cardiac magnetic resonance (MR) imaging for further evaluation of the atrial mass. Because of the suspected diagnosis, conventional radiography of the skeleton was performed.

[A man in his forties with swelling in both orbits]

Erdheim-Chester disease. A multi-disiplinary challenge. The histiocytoses are a diverse, but rare group of disorders with symptoms affecting many organs, varying from self-limiting, localised lesions to disseminated multi-organ disease. The diagnostic challenges are illustrated and discussed in the following case.

CASE REPORT

A man in his forties was admitted to hospital due to pain in his right eye and visual disturbances. MRI imaging detected a mass in his right orbit and a minor mass in his left orbit. The histological results of the mass in his right orbit revealed an inflammatory process with lymphocytes and macrophages and no sign of vasculitis, infection or malignancy. The diagnosis pseudotumor orbita was made and treatment with corticosteroids was initiated. He did not respond to corticosteroids or radiotherapy and increasing symptoms necessitated rehospitalisation. Further tests disclosed a multisystem disease which affected the aorta, skeleton, lung, heart and kidney. The biopsy was reconsidered and the disease was classified as a histiocytosis with CD68 positive and CD1a negative cells. The diagnosis Erdheim-Chester was given, about 14 months after the initial hospitalisation. Treatment with interferon α was started.

FDG PET images in a patient with Erdheim-Chester disease

Erdheim-Chester disease is an uncommon non-Langerhans-cell histiocytosis, due to excessive production of histiocytes deposited in various organs and tissues in the human body. FDG PET was performed in a 68-year-old man with documented active Erdheim-Chester disease to evaluate the extent of the disease. The patient was previously treated with high-dose subcutaneous Interferon α2b, 1,000,000 units 3 times a week, but treatment was interrupted approximately 5 weeks before evaluation at the National Institutes of Health because of adverse effects of the medication. FDG PET/CT showed lesions were imaged in brain, heart, mediastinum, abdomen, and skeleton.

Thoracic, abdominal and musculoskeletal involvement in Erdheim-Chester disease: CT, MR and PET imaging findings

BACKGROUND

Erdheim-Chester disease (ECD) is a rare, non-Langerhans cell histiocytosis with characteristic radiological and histological features. This entity is defined by a mononuclear infiltrate consisting of lipid-laden, foamy histiocytes that stain positively for CD68 and negatively for CD1a. Osseous involvement is constant and characteristic. Extra-osseous lesions may affect the retroperitoneum, lungs, skin, heart, brain and orbits.

METHODS

Both radiography and technetium-99m bone scintigraphy may reveal osteosclerosis of the long bones, which is a typical finding in ECD. For visceral involvement, computed tomography (CT) is most useful, while magnetic resonance (MR) imaging is more sensitive for cardiovascular lesions; 2-[fluorine-18] fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET)/CT scanning is useful in assessing the extension of ECD lesions.

RESULTS

The prognosis is extremely variable and is often worse when there is cardiovascular system involvement. Diagnosis is based on the combination of radiographic, CT, MR imaging and nuclear medicine features and a nearly pathognomonic immunohistochemical profile.

CONCLUSION

The aims of this work are to perform a systematic review of Erdheim-Chester disease as seen on imaging of the chest, abdomen and musculoskeletal system and to discuss the diagnostic workup and differential diagnoses according to the imaging presentation. Teaching points • Bone involvement is usually present in patients, and the imaging findings are pathognomonic of ECD. • The circumferential periaortic infiltration may extend to its branches, sometimes becoming symptomatic. • Cardiac involvement-the pericardium, right atrium and auriculoventricular sulcus-worsens its prognosis. • Perirenal infiltration extending to the proximal ureter is highly suggestive of this disease.

Association of both Langerhans cell histiocytosis and Erdheim-Chester disease linked to the BRAFV600E mutation

Histiocytoses are a group of heterogeneous diseases that mostly comprise Langerhans cell histiocytosis (LCH) and non-LCH. The association of LCH with non-LCH is exceptional. We report 23 patients with biopsy-proven LCH associated with Erdheim-Chester disease (ECD) (mixed histiocytosis) and discuss the significance of this association. We compare the clinical phenotypes of these patients with those of 56 patients with isolated LCH and 53 patients with isolated ECD. The average age at diagnosis was 43 years. ECD followed (n = 12) or was diagnosed simultaneously with (n = 11) but never preceded LCH. Although heterogeneous, the phenotype of patients with mixed histiocytosis was closer to that of isolated ECD than to that of isolated LCH (principal component analysis). LCH and ECD improved in response to interferon alpha-2a treatment in only 50% of patients (8 of 16). We found the BRAF(V600E) mutation in 11 (69%) of 16 LCH lesions and in 9 (82%) of 11 ECD lesions. Eight patients had mutations in both ECD and LCH biopsies. Our findings indicate that the association of LCH and ECD is not fortuitous and suggest a link between these diseases involving the BRAF(V600E) mutation.

Multidetector computed tomographic imaging of Erdheim-Chester disease

Erdheim-Chester disease is a rarely reported disease that can affect nearly every organ and chiefly infiltrates the connective, perivascular, and adipose tissue. The disease is a form of non-Langerhans-cell histiocytosis characterized by the proliferation of foamy histiocytes; its cardiovascular complications carry a severe prognosis. We present the case of a 29-year-old woman who was admitted for analysis of her angina. Our evaluation with use of cardiac multidetector computed tomographic angiography revealed large mediastinal soft tissue that compressed the patient's left anterior descending coronary artery. To our knowledge, this is the first report of the use of low-dose, dual-source, 256-slice multidetector computed tomography to characterize Erdheim-Chester disease that exclusively caused angina and stenosis of a coronary artery in a young adult.