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

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.

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 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.

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.

Novel paraneoplastic mechanism for cerebellar ataxia in Erdheim-Chester disease

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

Radiological findings in Erdheim Chester disease: A very rare multisistemic disease

Erdheim-Chester disease is an uncommon non-Langerhans cell histiocytosis affecting multiple systems. There is limited knowledge on the imaging capabilities of this disease. We present an extremely rare case of Erdheim-Chester illness in a 67-year-old man with multisystem involvement, including the cardiovascular system, skeleton, retroperitoneum (renal and adrenal infiltration) and the neurologic system. The involvement of the various organs was thoroughly assessed using multimodal imaging modalities such as computed tomography, magnetic resonance imaging, positron emission tomography and bone scintigraphy. Erdheim-Chester illness was revealed by a bone biopsy. Especially when there is cardiac and cerebral involvement, Erdheim-Chester illness is a rare condition with a poor prognosis. Knowing the imaging characteristics of Erdheim-Chester disease may be helpful in understanding the radiological results of many organs affected by the disease as described and discussed in the current case report.

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

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

Erdheim-Chester disease: diffusion-weighted imaging and dynamic contrast-enhanced MRI provide useful information

This is, to our knowledge, the first case report with in-depth analysis of bone marrow and bone lesions with diffusion-weighted imaging and dynamic contrast-enhanced MRI in Erdheim-Chester disease to date. We present a case of a 70-year-old woman who was referred for an X-ray of the pelvis, right femur and right knee after complaints of migratory arthralgia in hip and knee five months after an initial hip and knee trauma. Bone lesions on X-ray were identified. This case report highlights the strength and complementary use of modern multimodality multiparametric imaging techniques in the clinical radiological manifestations of Erdheim-Chester disease, in the differential diagnosis and in treatment response assessment, which is classically performed using ¹⁸FDG PET-CT. Erdheim-Chester disease is a rare form of non-Langerhans' cell histiocytosis, mainly affecting individuals in their fifth-seventh decade of life and without sex predominance. Apart from the typical bilateral symmetric lesions in long bone diaphyseal and metaphyseal regions and classically sparing the epiphyses, this multisystemic disease causes significant morbidity by infiltrating critical organs (the central nervous system, cardiovascular system, retroperitoneum, lungs and skin). With non-traumatic bone pain being the most common complaint, Erdheim-Chester disease is diagnosed most often in an incidental setting on imaging. The imaging workup classically consists of a multimodality approach using conventional radiography, CT, MRI, bone scintigraphy and ¹⁸FDG PET-CT. This case report extends this evaluation with diffusion-weighted imaging and dynamic contrast-enhanced imaging techniques.

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

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

Rare presentation of multiple thromboses in Erdheim-Chester disease: a case-based review

BACKGROUND

ECD is a rare non-Langerhans cell histiocytosis with diverse and heterogeneous clinical manifestations, ranging from single-lesion forms to multi-system involvement, including slowly progressing unifocal forms to rapidly evolving life-threatening disease.

CASE PRESENTATION

A female patient presented with a 2-month history of fever. Imaging revealed multiple thromboses, bone destruction, an abnormal pituitary stalk, and clinical manifestations of diabetes insipidus. Excisional biopsy of a tibial lesion was sent for microscopic examination, and subsequent immunohistochemical testing was positive for expression of CD68 and CD163, and negative for expression of the immune markers CD1a, S100, and langerin. This confirmed the diagnosis of ECD. Treatment with methylprednisolone to inhibit the immune inflammatory response along with anti-cytokine therapy with an interleukin-6 antagonist resulted in satisfactory disease control.

CONCLUSION

We report a rare case of multiple thromboses, embolism, and multiple organ involvement as the main presentation of ECD, suggesting that ECD should be considered in patients presenting with multiple thromboses associated with multisystem damage. We successfully treated our patient with glucocorticoids and interleukin-6 antagonist. This patient's response to treatment suggests that hormone therapy and cytokine/chemokine therapy may be a potential novel treatment for patients with ECD without gene mutations.

Role of 18 F-FDG PET/CT in Erdheim-Chester Disease in the Era of Multimodality Imaging

Erdheim–Chester disease is a rare disease with systemic non-Langerhans cell histiocytosis, the diagnosis of which with conventional imaging modalities is challenging. We describe a case of a 73-year-old woman who was referred with a progressive history of bilateral proptosis. The magnetic resonance imaging (MRI) orbit demonstrated bilateral orbital masses with optic nerve encasement. A subsequent 18F-FDG PET/CT scan showed multi-organ disease with involvement of the orbits, pericardium, aorta, pararenal fascia, and appendicular bones. Metabolically active, easily accessible areas were selected for CT-guided biopsy. The biopsy showed sheets of foamy histiocytes with the expression of CD 68 and CD 163 consistent with a diagnosis of Erdheim–Chester disease. The FDG PET/CT played a pivotal role in establishing the diagnosis with the assessment of disease extent and further guided in the targeted biopsy.

Erdheim-Chester disease with long-standing diabetes insipidus and generalized edema

Erdheim-Chester disease (ECD) is a rare non-Langerhans histiocytosis. ECD is detected more frequently due to increased awareness of healthcare providers and improved diagnostic tools. This report describes a 51-year-old woman with a history of weakness, bone pain, xanthelasma palpebrarum, and diabetes insipidus. ECD is a multisystemic condition with a poor prognosis. This disease should be considered in patients with diabetes insipidus, bone pain, and multiorgan involvements.

Urinary involvement in Erdheim-Chester disease: computed tomography imaging findings

PURPOSE

To describe the urological manifestations of Erdheim-Chester disease (ECD) and their computed tomography (CT) findings.

METHODS

We retrospectively reviewed 48 patients diagnosed with ECD at Peking Union Medical College Hospital from January 2014 to January 2020. Twenty-four patients exhibited urological manifestations. Their CT findings, including appearances of the involved area (e.g., perirenal space, renal sinus, ureters, renal arteries, and adrenal glands), occurrence rate of ECD involvement in each area, signal enhancement pattern after CT contrast agent administration, disease progression, and causes of hydronephrosis were discussed.

RESULTS

In 24 patients with evidence of ECD urological involvement, the most common manifestation was perirenal infiltration, appearing as "hairy kidney" on unenhanced CT scans and moderate signal enhancement on enhanced CT scans (17/24, 70.8%). Other manifestations included renal sinus infiltration (16/24, 66.7%), proximal ureter involvement (14, 58.3%), renal artery sheath (10, 41.7%), hydronephrosis (14, 58.3%), and adrenal glands involvement (8, 33.3%). The histiocytic infiltrate was mostly bilateral, starting from the perirenal space and spreading to the renal sinus and ureters. Hydronephrosis was usually associated with infiltration of ureters.

CONCLUSION

Kidneys are the most common visceral organs affected by ECD. CT scanning is not only advantageous in early diagnosis, but also critical for designing the treatment regime for patients with ECD.

Aortic Fistulas: Pathophysiologic Features, Imaging Findings, and Diagnostic Pitfalls

Fistulas between the aorta and surrounding organs are extremely rare but can be fatal if they are not identified and treated promptly. Most of these fistulas are associated with a history of trauma or vascular intervention. However, spontaneous aortic fistulas (AoFs) can develop in patients with weakened vasculature, which can be due to advanced atherosclerotic disease, collagen-vascular disease, vasculitides, and/or hematogenous infections. The clinical features of AoFs are often nonspecific, with patients presenting with bleeding manifestations, back or abdominal pain, fever, and shock. Confirmation with invasive endoscopy is often impractical in the acute setting. Imaging plays an important role in the management of AoFs, and multiphasic multidetector CT angiography is the initial imaging examination of choice. Obvious signs of AoF include intravenous contrast material extravasation into the fistulizing hollow organ, tract visualization, and aortic graft migration into the adjacent structure. However, nonspecific indirect signs such as loss of fat planes and ectopic foci of gas are seen more commonly. These indirect signs can be confused with other entities such as infection and postoperative changes. Management may involve complex and staged surgical procedures, depending on the patient's clinical status, site of the fistula, presence of infection, and anticipated tissue friability. As endovascular interventions become more common, radiologists will need to have a high index of suspicion for this entity in patients who have a history of aneurysms, vascular repair, or trauma and present with bleeding. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article. ^©RSNA, 2021.

Central Nervous System Complications of Erdheim-Chester Disease: FDG PET/CT Findings

ABSTRACT

Erdheim-Chester disease is an uncommon non-Langerhans cell histiocytosis. The diagnosis depends on imaging and histological criteria. The most common presentation is the multiple bone lesions with involvement of at least 1 more organ. We present the FDG PET/CT findings of a 19-year-old man who presented with central nervous system symptoms such as progressive polyuria, polydipsia, gait disturbances, and eye pain and was later diagnosed with Erdheim-Chester disease.

Sclerotic bone lesions caused by non-infectious and non-neoplastic diseases: a review of the imaging and clinicopathologic findings

Bone sclerosis is a focal, multifocal, or diffuse increase in the density of the bone matrix on radiographs or computed tomography (CT) imaging. This radiological finding can be caused by a broad spectrum of diseases, such as congenital and developmental disorders, depositional disorders, and metabolic diseases. The differential diagnosis can be effectively narrowed by an astute radiologist in the light of the clinical picture and typical findings on imaging. Some of these lesions are rare and have been described as case reports and series in the literature. This article aims to collate the clinical-radiologic findings of non-infectious and non-neoplastic causes of bone sclerosis with relevant imaging illustrations.

Erdheim-Chester Disease: A Case of Right Atrial Involvement and Superior Vena Cava Stenosis

We describe the case of a 79-year-old woman with a history of Erdheim-Chester disease who presented with bradyarrhythmia and infiltration of the superior vena cava and right atrium. This case highlights an important consideration in type of pacemaker placement given the frequency of right atrial involvement in Erdheim-Chester disease. (Level of Difficulty: Advanced.)

Non-neoplastic conditions mimicking peritoneal carcinomatosis at CT imaging

The general appearance of peritoneal carcinomatosis at abdominal CT and other cross-sectional imaging modalities consists of varying amounts of peritoneal-based soft tissue implants (mass-forming or infiltrative), peritoneal fluid, and occasionally calcification. However, a wide variety of common and uncommon neoplastic and non-neoplastic conditions can closely mimic peritoneal carcinomatosis at imaging. Neoplastic mimics of peritoneal carcinomatosis include primary peritoneal and sub peritoneal tumors, as well as peritoneal lymphomatosis and sarcomatosis.Broad categories of non-neoplastic mimics of peritoneal carcinomatosis include tumor-like conditions, systemic processes, atypical infections, and fat-based conditions. For many entities, suggestive or specific patient information and/or CT imaging findings exist that may allow the radiologist to narrow the differential diagnosis. In this article, we review the salient clinical and cross-sectional imaging features of non-neoplastic mimics of peritoneal carcinomatosis and malignancy, with emphasis on the CT findings and the additional clues that may suggest the correct benign diagnosis.

Clinical presentation, imaging and response to interferon-alpha therapy in Erdheim-Chester disease: case-based review

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis associated with BRAFV600E mutations in more than 50% of cases and presenting with 95% with skeletal lesions. However, cutaneous, pulmonary, large vessels and central nervous system involvement can also occur. We report a case of a 25-year-old woman who was admitted in 2018 for exploration of diffuse bone pain and rashes on the face. Her current symptoms had started 14 months earlier and consisted of bone pain, affecting the legs. She had periodic low-grade fever, asthenia and xanthelasma-like papules appeared on face. At admission, physical examination showed bilateral and symmetrical long bone pain, especially in the knees and multiple xanthelasma-like papules around the eyelids, cheeks and chin. Laboratory tests revealed elevated erythrocyte sedimentation rate and C-reactive protein. Magnetic resonance (MR) imaging showed multiple mixed bone lesions with a hyperintensive MR signal on PD FS and hypointense signal on T1of the femur and tibia. Bone scintigraphy indicated bilateral and symmetrical metaphyseal and diaphyseal increased uptake. Abdominal computed tomography (CT) scan showed infiltration of the perirenal fat. Biopsy of the skin revealed histiocytic infiltration, which was CD68-positive and CD100-positive, confirming the diagnosis of ECD. Patient was treated with interferon-α (IFN-α) plus methylprednisolone. After 6 months of treatment her clinical condition partly improved: a reduction of pain on visual analogue scale (VAS) scale, significant decrease of methylprednisolone dose and specific dynamics according to bone MR imaging data, however, no change in symptoms attributed to skin rash was noted. We also provide the literature review results of IFN-α treatment efficacy in Erdheim-Chester disease involving the skin and musculoskeletal system with MR imaging changes.

Erdheim-Chester disease

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

Unusual manifestations of diffuse-type tenosynovial giant cell tumor in two patients: importance of radiologic-pathologic correlation

Diffuse-type tenosynovial giant cell tumor (TSGCT) is a rare, locally aggressive neoplasm. It most commonly occurs in the knee, followed by the hip, and has distinctive imaging features, including mass-like foci of low T2 signal intensity, "blooming" on gradient-echo MRI, and pronounced uptake on FDG PET/CT. Histologically, TSGCT demonstrates a neoplastic population of mononuclear cells admixed with hemosiderin-laden macrophages, foamy histiocytes, inflammatory cells, and osteoclast-like giant cells. In cases where diffuse-type TSGCT presents in an uncommon location or with atypical features, the imaging diagnosis may be challenging. Furthermore, because of its polymorphous appearance, it may be mistaken microscopically for other neoplastic and non-neoplastic histiocytic lesions. Herein, we present two cases of diffuse-type TSGCT presenting as large masses, and underscore the importance of radiologic-pathologic correlation for accurate diagnosis.

Clinical Nononcologic Applications of PET/CT and PET/MRI in Musculoskeletal, Orthopedic, and Rheumatologic Imaging

OBJECTIVE

With improvements in PET/CT and PET/MRI over the last decade, as well as increased understanding of the pathophysiology of musculoskeletal diseases, there is an emerging potential for PET as a primary or complementary modality in the management of rheumatologic and orthopedic conditions.

CONCLUSION

We discuss the role of PET/CT and PET/MRI in nononcologic musculoskeletal disorders, including inflammatory and infectious conditions and postoperative complications. There is great potential for an increased role for PET to serve as a primary or complementary modality in the management of orthopedic and rheumatologic disorders.

A new role for fluorine-18-fluorodeoxyglucose positron-emission tomography/computed tomography in Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a rare form of non-Langerhans cell histiocytosis, with multisystem manifestation such as bone pain, being the most common presenting symptom, cardiovascular or central nervous system involvement, interstitial lung disease, skin and orbital lesions, adrenal enlargement, retroperitoneal fibrosis and renal impairment as well fever, and weight loss. The disease is challenging to diagnose due to its rarity and mimicry of other infiltrative processes. Technetium-99 m bone scintigraphy showing pathological bone activity in the long bones is highly suggestive of ECD. However, not all patients have bone complaints. Till now, fluorine-18-fluorodeoxyglucose positron-emission tomography/computed tomography (¹⁸F-FDG PET/CT) was especially used after histological diagnosis to determine disease activity and extent, as well as the evaluation of treatment response. With this case, we suggest an additional role for ¹⁸F-FDG PET/CT earlier on in the diagnosis workup as follows: detecting a possible biopsy site to establish the diagnosis of ECD especially in a clinical context without bone pain.

The imaging appearances of various pericardial disorders

The pericardium could be involved in a variety of clinical disorders. The imaging findings are not specific for an individual pathology in most of the cases; however, patient’s clinical history may guide radiologist to a definitive diagnosis. Congenital absence of the pericardium could be recognized with the imaging appearance of interposed lung tissue between the main pulmonary artery and aorta. Pericardial effusion is a non-specific condition that may occur due to inflammatory, infectious, and neoplastic disorders. Cardiac tamponade may occur in case of massive or rapid accumulation of fluid in the pericardial sac. Pericardial calcification is a common and easily identified entity on a computed tomography (CT) scan. Presence of calcification and/or fibrosis may result in pericardial constriction. Nevertheless, the pulsation of an adjacent coronary artery may prevent calcification formation in a focal area and consequently may result in pericardial diverticulum containing epicardial fat and coronary artery. The imaging findings encountered in patients with pericardial hydatid disease and Erdheim-Chester disease may mimic those of pericardial neoplasia. Pericardial adhesions and pedicled fat flaps may cause confusion on a CT scan in the post-surgical period following cardiac surgery. Pericardial fat necrosis can be diagnosed by CT in patients with chest pain. The radiologists should be familiar with the medical devices placed in pericardial space for certain individual indications. A pericardial patch and temporary epicardial pacemaker wires could be identified on a CT scan.

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.

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.

FDG PET/CT Findings of Erdheim-Chester Disease: Radiologic Response to a Novel Treatment Regimen

Erdheim-Chester disease (ECD) is a rare form of non-Langerhans histiocytosis with deposition of lipid-laden macrophages in numerous organs. A 74-year-old man with a history of coronary artery disease, hypertension, and hyperlipidemia presented with nonspecific symptoms including back pain, nausea, vomiting, vertigo, and left leg pain. A neutrophil-predominant elevated WBC count and a bone biopsy revealing histiocytic proliferation positive for CD68 and CD163 and negative for S100 was noted. FDG PET/CT, MRA, and CTA images were obtained. We review the radiologic hallmarks of ECD and demonstrate the radiologic manifestations of response to combined BRAF and MEK inhibitor treatment.

Imaging findings in Erdheim-Chester disease: what every radiologist needs to know

Erdheim-Chester disease (ECD) is a rare sporadic non-Langerhans cell histiocytic (LCH) proliferative disorder with systemic predilection. It usually affects adults in the 5th-7th decades of life and has non-specific clinical manifestations. Its suspicion is often heralded by the presence of characteristic radiological findings and subsequently confirmed by demonstration of CD68-positive xanthogranulomatous infiltrates on histopathology. Despite being a non-malignant entity, it might be fatal due to organ dysfunction. Imaging plays a key role in the diagnosis, management, and follow-up. Imaging findings are essential to establish the diagnosis, assess actual disease burden, and explore the aetiopathogenesis and therapeutic options to halt disease progression and associated morbidity.

18F-FDG PET/CT in Erdheim-Chester Disease: Imaging Findings and Potential BRAF Mutation Biomarker

The purpose of this study was to evaluate ¹⁸F-FDG PET/CT for the diagnosis, management, and treatment of Erdheim-Chester disease (ECD). Methods: Our institutional database (2007-2017) was retrospectively reviewed for patients with pathologically proven ECD. A chart review yielded demographics, clinical information, and 5 categories of clinical impact. Two radiologists in consensus interpreted the images. Imaging findings were correlated with clinical data. Results: Seventy-one ¹⁸F-FDG PET/CT examinations were performed for 32 patients. The average SUV_max of the most active disease site was 9.2 (SD, 6.1). The most common sites involved were the skeleton (90.6% of patients, including 47% with axial and pelvic skeletal involvement), kidneys (81.3%), and central nervous system (CNS) (46.9%). Twenty-six patients were tested for a proto-oncogene B-Raf ^V600E (BRAF) mutation (18 had the mutation and 8 did not). The presence of a BRAF mutation was associated with ¹⁸F-FDG-avid CNS disease (P = 0.0357), higher SUV_max (P = 0.0044), and greater mortality (P = 0.0215). The presence of CNS disease had 88% specificity and a 92% positive predictive value for predicting the presence of a BRAF mutation. PET/CT examination results influenced patient management in 48% of cases (34/71). Conclusion:¹⁸F-FDG PET/CT results may act as a biomarker for the presence of a BRAF mutation, aid in establishing a diagnosis, guide biopsies, and gauge the treatment response in ECD patients. Axial and pelvic skeletal involvement is greater than previously reported.

Benign Bone Conditions That May Be FDG-avid and Mimic Malignancy

Positron emission tomography with the radiotracer ¹⁸F-fluoro-2-deoxy-d-glucose (FDG) plays an important role in the evaluation of bone pathology. However, FDG is not a cancer-specific agent, and knowledge of the differential diagnosis of benign FDG-avid bone alterations that may resemble malignancy is important for correct patient management, including the avoidance of unnecessary additional invasive tests such as bone biopsy. This review summarizes and illustrates the spectrum of benign bone conditions that may be FDG-avid and mimic malignancy, including osteomyelitis, bone lesions due to benign systemic diseases (Brown tumor, Erdheim-Chester disease, Gaucher disease, gout and other types of arthritis, Langerhans cell histiocytosis, and sarcoidosis), benign primary bone lesions (bone cysts, chondroblastoma, chondromyxoid fibroma, desmoplastic fibroma, enchondroma, giant cell tumor and granuloma, hemangioma, nonossifying fibroma, and osteoid osteoma and osteoblastoma), and a group of miscellaneous benign bone conditions (post bone marrow biopsy or harvest status, bone marrow hyperplasia, fibrous dysplasia, fractures, osteonecrosis, Paget disease of bone, particle disease, and Schmorl nodes). Several ancillary clinical and imaging findings may be helpful in discriminating benign from malignant FDG-avid bone lesions. However, this distinction is sometimes difficult or even impossible, and tissue acquisition will be required to establish the final diagnosis.

[Usefulness of nuclear medicine in Erdheim-Chester disease: A Lille experience]

INTRODUCTION

Erdheim-Chester disease is a rare form of non-langerhans histiocytosis and its etiology is still not well established. The aims of the study were to assess the value of the bone scintigraphy and the ¹⁸F-FDG PET/CT for the diagnostic and for the latter in the therapeutic evaluation.

METHODS

We retrospectively reviewed 49 patients suspected of Erdheim-Chester disease between 2004 and 2016. Bone scintigraphy was compared with histopathology and PET-CT to conventional morphological examinations and bone scintigraphy. For therapeutic evaluation, thresholds similar to PERCIST 1.0 were used.

RESULTS

Forty-nine bone scintigraphy were evaluated with a sensitivity of 100%, a specificity 97%, a positive predictive value 90% and a negative predictive value of 100%. Eight patients had at least an initial PET-CT. The sensitivity compared to conventional morphological examinations differed from the location but was excellent for orbital, bone and vascular involvements. Specificity was comparable between the different examinations. Six patients treated with interferon^® and three with vemurafenib^® were followed by PET-CT. PET-CT, in agreement to clinicobiological data, identified 4 partial responses and one complete response with interferon^® et two partial responses and one complete response with vemurafenib^®.

CONCLUSION

Our retrospective study suggests that bone scintigraphy and 18F-FDG PET/CT could be useful in the initial assessment of Erdheim-Chester disease but also for the latter in the therapeutic evaluation.

18F-FDG PET/CT in follow-up evaluation in pediatric patients with Langerhans histiocytosis

PURPOSE

We evaluated the impact of ¹⁸F-FDG PET/CT in identifying sites of active disease and to assess therapeutic follow up in a group of pediatric patients with Langerhans cell histiocytosis (LCH).

METHOD

During 2007-2013, 13 ¹⁸F-FDG PET/CT studies were performed for follow-up in 7 patients with a diagnosis of LCH (4 female, 3 male; 1-12 years-old). PET findings were analyzed and correlated with the CT and MRI. Findings were also follow-up by these techniques.

RESULTS

PET was negative in 4 patients (all diagnosed with bone lesions and one with pituitary involvement also). CT findings showed residual morphological bone lesions in all patients, and hypophysis MRI study showed no abnormal signal. PET remained negative at 10, 14, 25 and 28 months, and no new lesions on CT and MRI were detected. PET was positive in 3 patients (one with cervical lymphadenopathy and 2 with bone lesions, one also with pituitary involvement not identified by PET). CT findings showed pathological cervical lymphadenopathy (n=1), bone lesions (n=2) and also a pituitary MRI lesion (n=1). In a patient with cervical lymphadenopathy histology demonstrated LCH involvement. In the other 2 patients, PET remained positive with an increase of ¹⁸F-FDG bone uptake at 17 and 19 months.

CONCLUSION

In our preliminar study, ¹⁸F-FDG PET is a useful imaging procedure, along with other diagnostic tools, for identification of active lesions.

Radiological diagnosis of perinephric pathology: pictorial essay 2015

The perinephric space, shaped as an inverted cone, sits between the anterior and posterior renal fasciae. It can play host to a variety of clinical conditions encountered daily in the reporting schedule for a radiologist. Lesions may be classified and diagnosed based on their imaging characteristics, location and distribution. A broad range of differential diagnoses can be attributed to pathology sitting within this space, often without clinical signs or symptoms. An understanding of commonly encountered conditions affecting the perinephric space, along with characteristic imaging findings, can illustrate and often narrow the likely diagnosis. The aim of this essay is to describe commonly encountered neoplastic and non-neoplastic entities involving the perinephric space and to describe their key imaging characteristics.

TEACHING POINT

• Despite often a bulky disease, perinephric lymphoma does not produce obstruction or stenosis. • In primarily fatty masses, defects within the renal capsule likely represent angiomyolipoma. • Consider paraganglioma if biopsy is planned; biopsy may lead to catecholamine crisis.

Unusual presentation of Erdheim-Chester disease in a child with acute lymphoblastic leukemia

Erdheim-Chester disease (ECD) is an uncommon, non-familial, non-Langerhans cell histiocytosis, which involves skeletal system and soft tissue usually in middle aged and elderly patients. The characteristic radiologic features include bilateral, symmetric cortical osteosclerosis of the diaphyseal and metaphyseal parts of the long bones, or bilateral symmetrically abnormal intense ^99mTechnetium labelling of the metaphyseal-diaphyseal region of the long bones, and computed tomography scan findings of “coated aorta” or “hairy kidneys”. ECD in childhood with osteolytic lesion is extremely rare. We describe an unusual case with an expansile lytic bone lesion at presentation in a case of acute lymphoblastic leukemia.

Diseases and Syndromes That Affect the Lungs and the Kidneys: A Radiologic Review

A number of different conditions simultaneously affect both the lungs and the kidneys. These include autoimmune disorders and genetic tumor syndromes. Although manifestations within either organ system alone may not be specific, by observing the pattern of involvement and clinical history, radiologists may be able to suggest the correct diagnosis.

The First Reported Case of Erdheim-Chester Disease in Egypt with Bilateral Exophthalmos, Loss of Vision, and Multi-Organ Involvement in a Young Woman

Patient: Female, 19

Final Diagnosis: Erdheim-Chester disease

Symptoms: Exophthalmos, orthopnea

Medication: Prednisolone • azathioprine

Clinical Procedure: —

Specialty: Internal Medicine

Cardiovascular Involvement in Erdheim-Chester Disease: A Case Report and Review of the Literature

Erdheim-Chester disease (ECD) is a rare, multiorgan, non-Langerhans cell histiocytosis of uncertain origin, characterized by systemic xanthogranulomatous infiltration from CD68+CD1a- histiocytes. Skeletal involvement is present in up to 96% of cases with bilateral osteosclerosis of meta-diaphysis of long bones. Furthermore, in more than 50% of cases there is 1 extraskeletal manifestation. In this case report, we describe an interesting case of ECD with an extensive pan-cardiac and vascular involvement, in addition to skeletal, retro-orbital, and retroperitoneum one.A 44-year-old woman with a long history of exophthalmos referred to our hospital for elective surgical orbital decompression. At preoperative examinations a large pericardial effusion was discovered. Echocardiography, computed tomography (CT), and magnetic resonance imaging (MRI) described an inhomogeneous mass involving pericardium and the right heart, abdominal aorta and its main branches and the retroperitoneum, suggestive for a systemic inflammatory disorder. Histological examination on a biopsy sample confirmed the diagnosis of ECD. Radiology showed the pathognomonic long-bone involvement. Surgical orbital decompression was performed and medical therapy with interferon-α (INF-α) was started.Among extraskeletal manifestations of ECD, cardiovascular involvement is often asymptomatic and thus under-diagnosed but linked to poor prognosis. This is why clinician should always look for it when a new case of ECD is diagnosed.

The role of 18FDG, 18FDOPA PET/CT and 99mTc bone scintigraphy imaging in Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocitosis, characterized by multisystemic xanthogranulomatous infiltration by foamy histiocytes that stain positively for CD68 marker but not express CD1a and S100 proteins. Etiology and pathogenesis are still unknown and only about 500 cases are related in the literature. Multisystemic involvement leads to a wide variety of clinical manifestations that results in a poor prognosis although recent advances in treatment. We present the clinical, nuclear medicine findings and therapeutic aspects of a serie of 6 patients with histopathological diagnosis of ECD, who have undergone both bone scintigraphy (BS) and 18F-fluorodeoxyglucose (18FDG)-PET/CT scans in our institution. A complementary 18F-fluorodopa (18FDOPA)-PET/CT was performed in one case. Three different presentations of the disease were observed in our casuistic: most indolent form was a cutaneous confined disease, presented in only one patient. Multifocal involvement with central nervous system (CNS) preservation was observed in two patients. Most aggressive form consisted in a systemic involvement with CNS infiltration, presented in three patients. In our experience neurological involvement, among one case with isolate pituitary infiltration, was associated with mortality in all cases. 18FDG-PET/CT and BS were particularly useful in despite systemic involvement; locate the site for biopsy and the treatment response evaluation. By our knowledge, 18FDOPA-PET/CT not seems useful in the initial staging of ECD. A baseline 18FDG-PET/CT and BS may help in monitoring the disease and could be considered when patients were incidentally diagnosed and periodically 18FDG-PET/CT must be performed in the follow up to evaluate treatment response.

Computed tomography and magnetic resonance imaging findings of ureteral myxedema in Graves' disease

Ureteral myxedema is exceptionally rare. We describe computed tomography and magnetic resonance imaging findings in a case of ureteral myxedema. The demonstration of water-like hyperintensity around the ureteral lumen on heavily T2-weighted sequences should be considered a strongly suggestive sign for ureteral myxedema.