Erdheim–Chester disease (ECR 2014 Case of the Day)

Clinical History

A 44-year-old woman with history of progressive and bilateral exophthalmos refractory to conventional therapies referred to our Emergency Department for sudden painless vision loss in the left eye. She complained also of shortness of breath and dry cough. Laboratory blood tests including thyroid function were within normal limits.

Imaging Findings

Head CT showed bilateral homogeneous retrobulbar soft tissue (Fig.1a). A left-sided 3-wall orbital decompression was performed to reduce optic nerve compression (Fig.1b), bone/soft tissue specimens were sent for histological examination. Brain MRI confirmed intraconal tissue surrounding optic nerves hypointense on T2WI, with homogeneous enhancement on contrast-enhanced T1WI (Fig.2a,b). Chest radiograph revealed diffuse interstitial involvement, fissural thickening and enlarged cardiac image (Fig.3). High-resolution chest CT showed smooth interlobular septal thickening, pleural and pericardial effusion (Fig.4a,b). Soft tissue infiltrating right atrium wall and surrounding right coronary artery was observed at CT mediastinal window (Fig.4c). On cardiac MRI tissue showed hypointensity on T2WI and delayed enhancement on contrast-enhanced T1WI (Fig.5a,b). Diffuse retroperitoneal soft tissue was evident around aorta, renal arteries, kidneys and ureters (Fig.6a,b). Digital pyelography showing right pelvicaliectasis due to obstruction of proximal ureter was performed for nephrostomy placement (Fig.7). Radiograph of distal femurs demonstrated symmetric cortical sclerosis of meta-diaphyseal regions (Fig.8).

Discussion

Erdheim–Chester disease (ECD) is a rare systemic non-Langerhans cell histiocytosis of unknown origin, characterized by infiltration of tissues by foamy CD68+/CD1a- histiocytes surrounded by fibrosis [1]. The most common sites of involvement are the skeleton, CNS, cardiovascular system, lungs, retroperitoneum, skin; although cases of thyroid, testes and lymph nodes infiltration have also been reported [1, 2]. Diagnosis of ECD is particularly challenging since multiorgan involvement determines heterogeneous clinical manifestations with variable prognosis, ranging from asymptomatic bony lesions to multisystemic life-threatening disease [3]. Bone involvement is almost constant. Radiography and scintigraphy show pathognomonic features: respectively bilateral symmetric osteosclerosis and increased uptake of technetium-99 of meta-diaphysis of long bones [1, 4]. Extraosseous involvement is present in about half of patients [1, 3, 5]. Hypothalamic-pituitary infiltration leads to diabetes insipidus while retroorbital infiltration to bilateral painless exophthalmos. Diabetes insipidus, bilateral exophthalmos and bone pain compose the ECD diagnostic triad [1, 4]. CNS involvement can have proteiform manifestations with infiltrative, meningeal pattern or both [6, 7]. Retroperitoneal infiltration is relatively frequent. The "hairy kidney" appearance on CT due to bilateral infiltration of perirenal and posterior pararenal space is highly suggestive [8]. Infiltration of renal arteries can lead to hypertension [8]. Cardiovascular involvement typically manifests as pericardial effusion, right atrial wall thickening and circumferential periaortic tissue infiltration ("coated aorta"), extended even to aortic collaterals, including coronary arteries [8, 9]. In case of pulmonary ECD histiocytic infiltration follows a perilymphatic distribution, usually accompanied by fibrosis. High-resolution chest CT shows smooth symmetric interlobular and fissural thickening, multifocal areas of ground-glass attenuation, centrilobular micronodules, thin-walled cysts, pleural effusion [5, 8]. Involvement can be diffuse or predominant in upper or lower lobes resembling cardiogenic pulmonary oedema. Normal calibre of pulmonary veins may help in differential diagnosis. Because symptoms of ECD are often unspecific, the number of differential diagnosis is large. Lymphoma, multifocal fibrosclerosis, Langerhans cell histiocytosis and sarcoidosis should be considered due to their possible systemic involvement. Presence of pathognomonic radiological findings of ECD, in particular evidence of a diffuse systemic perivascular and perilymphatic involvement, can direct diagnosis. However histopathological confirmation is crucial for diagnosis. In our patient histological analysis of specimens showed a chronic inflammatory infiltrate rich in CD68+ histiocytes in the orbital bone and retroorbital soft tissue (Fig.9). To date there is no standard treatment for ECD. Interferon-α provides the best management strategy, with stabilization of the disease in most cases even though prognosis remains poor [1, 10].

Differential Diagnosis List

Final Diagnosis

Erdheim-Chester disease with involvement of multiple organ systems

URL:	https://www.eurorad.org/case/11919
DOI:	10.1594/EURORAD/CASE.11919
ISSN:	1563-4086