대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Erdheim-Chester disease

Radiologic Findings

Fig. 1. Chest radiograph showing increased peribronchovascular interstitial thickening with septal line thickening in both lungs, and cardiomegaly.
Figs. 2 and 3. Chest computed tomography (CT) scans showing smooth interlobular thickening mainly in both upper lobes.
Fig. 4. Chest CT scan showing diffuse infiltrative wall thickening in the right atrium.
Fig. 5. Chest CT scan showing mild perivascular soft tissue encircling the aorta.
Fig. 6. Fluorodeoxyglucose (FDG) positron emission tomography image showing avidly increased uptake of FDG in the infiltrative lesion in the right atrium.

Brief Review

Erdheim-Chester disease (ECD) is a rare sporadic non-Langerhans cell histiocytic (LCH) proliferative disorder with systemic predilection. It usually affects adults in the fifth to seventh decades of life, with a slight male predilection. It has nonspecific clinical manifestations depending on the site of involvement. Constitutional symptoms, such as fever, weight loss, and night sweats, are common. Overall, the skeletal system is the most common site of involvement, leading to bone pain, which is the presenting manifestation in nearly 96% of cases. The most common extraosseous manifestations are central diabetes insipidus and exophthalmos.
The clinical, radiologic, and light microscopic findings may be indistinguishable from those of LCH. It is often suspected in the presence of characteristic radiologic findings and is subsequently confirmed by histopathology.
Histopathologically, ECD is characterized by tissue infiltration by lipid-laden histiocytes. The demonstration of CD68 positivity in xanthogranulomatous histiocytic infiltrates with a simultaneous lack of CD1a and Birbeck granules is confirmatory, thereby aiding in differentiating ECD from LCH.
Imaging plays a key role in the diagnosis, management, and follow-up. Plain radiography and technetium-99m bone scintigraphy are useful in determining skeletal involvement. Computed tomography (CT) or magnetic resonance imaging are useful for the evaluation of thoracoabdominal and central nervous system (CNS) involvement. Fluorodeoxyglucose-positron emission tomography/CT is invaluable for the in vivo determination of disease activity during follow-up.
The lung parenchyma and pleura are affected in approximately 40%–50% of cases. Parenchymal involvement may be interstitial, alveolar, or combined. Patients tend to remain asymptomatic or may have progressive dyspnea or cough. The most frequent finding on CT is smooth interlobular and intralobular septal thickening. However, many other nonspecific findings, such as centrilobular nodules, cysts, consolidation, ground-glass attenuation, or pleural effusion, may also be observed. Septal thickening due to histiocytic infiltration has a lymphangitic distribution involving the peribronchovascular bundle, interlobular septa, and visceral pleura. Pleuroparenchymal involvement on imaging may be indistinguishable from other interstitial lung diseases such as LCH, sarcoidosis, pulmonary edema, or veno-occlusive disease. Interstitial involvement in ECD culminates in pulmonary fibrosis, leading to respiratory failure.
The appendicular skeleton, especially the long bones of the lower extremities, is a predilection site for ECD involvement. On plain radiographs, a characteristic symmetrical bilateral cortical sclerosis affecting the metaphyses and/or diaphyses of the long tubular bones is observed (Fig. 1). In certain cases, the lesions may be either mixed lytic–sclerotic or purely lytic, which may be radiologically indistinguishable from LCH.
Orbital involvement is frequent in ECD, leading to exophthalmos, which is usually bilaterally symmetrical.
Cardiovascular involvement is frequent in ECD and is seen in nearly three-fourths of cases. Although any part of the heart may be affected, the pericardium is the most commonly involved site. Pericardial involvement leads to pericardial thickening and effusion. Myocardial infiltration more frequently involves the right heart, especially the right atrium and atrioventricular groove. On imaging, there is a plaque-like, infiltrative, smooth thickening of the pericardium and/or myocardium that may involve the septum and valves.
Plaque-like perivascular soft tissue encircling the aorta and its branches is also observed in ECD.
The retroperitoneum including the kidneys is the most common extraosseous site of involvement.
CNS involvement is usually extra-axial, contiguous with the facial or orbital bones and may extend to the adjacent brain parenchyma.
ECD may potentially involve any site, including the skin, breast, lymph nodes, thyroid gland, testis, and visceral organs.
Despite being a nonmalignant entity, ECD can be fatal owing to organ dysfunction. Involvement of particular sites, such as the CNS and cardiovascular system, affects the prognosis based on the observed poor response to chemotherapy. Although therapeutic advances have lowered morbidity, the impact on mortality remains dismal, with reported 1- and 5-year overall survival rates of 96% and 68%, respectively.

Please refer to

Case 744,

References

1. Kumar, Pawan, et al. "Imaging findings in Erdheim-Chester disease: what every radiologist needs to know." Polish journal of radiology 83 (2018): e54.
2. Wittenberg, Keith H., Stephen J. Swensen, and Jeffrey L. Myers. "Pulmonary involvement with Erdheim-Chester disease: radiographic and CT findings." American Journal of Roentgenology 174.5 (2000): 1327-1331.

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