– Bilateral perirenal soft tissue thickening extending to the renal sinus, encasing the renal arteries and veins (blue arrows) There is mild dilatation of bilateral renal calyces from the retroperitoneal infiltration
– Soft tissue encasement of the descending aorta (red arrows)
– Left renal cyst (green arrow)
What is the most likely diagnosis?
What is the most likely diagnosis?
Erdheim-Chester disease
Teaching points
– Erdheim-Chester disease (ECD) is a non-Langerhans cell histiocytosis characterized by multiorgan xanthomatous infiltration
– The diagnosis is based on clinical, imaging, and histopathological features
– Patients with ECD may present with bone pain, diabetes insipidus, exophthalmos, constitutional symptoms, interstitial lung disease, ureteral obstruction, renal impairment, cardiac dysfunction and tamponade, cerebellar or pyramidal symptoms, and xanthelasma.
– ECD has a wide range of manifestations throughout the body
– Skeletal involvement is the most common. At imaging, there is bilateral patchy or diffuse symmetric osteosclerosis of the lower extremity metaphyses and diaphyses, with relative sparing of the subchondral surfaces. Radiographically, cortical thickening, coarsened trabeculae, medullary sclerosis, and loss of the corticomedullary differentiation may be demonstrated
– Kidneys and retroperitoneum are often involved
– CT and MRI may show ‘hairy kidney sign’ that is demonstrated as irregular symmetric infiltration of the bilateral perirenal and posterior pararenal spaces
– Obstructive uropathy may result from medial displacement of the ureters
– Periaortic soft tissue is often shown, which is known as ‘coated aorta sign’
– Pulmonary involvement has been reported in 15-35% of patients with ECD and includes smooth interlobular septal thickening, micronodules, ground-glass opacities, thickening of interlobar fissures, and parenchymal consolidation
– Chest radiographs will often show interstitial edema pattern with cardiomegaly and pleural effusions that do not respond to diuretics
– Orbital and central nervous system involvement are common findings. Retrobulbar masses that can cause proptosis and optic nerve edema may be present
– The hypothalamic-pituitary axis is the most common site affected within the central nervous system. Absence of the normal T1 hyperintense signal of the neurohypophysis occurs with enhancing nodular soft tissue of the pituitary stalk and posterior pituitary gland that results in central diabetes insipidus. Intra- and extra-axial cerebral and spinal lesions may be observed
– Treatment: Targeted therapy such as BRAF inhibitors, MEK inhibitors, interferon alfa, steroid therapy, radiotherapy, and surgery may be performed. There is no known cure for ECD and historically the prognosis has been poor
– In our case, a biopsy from the perirenal soft tissue was performed. The histopathological findings confirmed the diagnosis of ECD
