Correct!
2. ECD is characterized by tissue infiltration with foamy, lipid-laden macrophages

Erdheim-Chester disease (ECD) is a rare, multisystem non-Langerhans cell histiocytosis characterized by tissue infiltration with foamy, lipid-laden macrophages. Chronic inflammation and characteristic multinucleate “Touton” giant cells may be present. The etiology of the disorder is unknown.

Patients affected with ECD are usually adults, with an average age of presentation of 52 years of age, with men slightly more commonly affected than women. The disorder has rarely been reported in children. Some patients may be detected asymptomatically, whereas others have variable, multisystem involvement and may present with a wide variety of symptoms, as detailed below:

  1. General symptoms of weight loss, fever, fatigue, myalgias, night sweats, weakness, and arthralgias may be reported in patients with ECD.
  2. Osseous involvement, typically affecting long bones, is very common and may present with bone pain.
  3. Neurological manifestations include diabetes insipidus, ataxia, dysarthria, nystagmus, and hypopituitarism. Ocular ECD may resemble pseudotumor, with patients presenting with exopthalmos.
  4. Abdominal and retroperitoneal involvement often centers on the kidneys, creating a retroperitoneal fibrosis-like presentation, including renal failure.
  5. Skin xanthomas may be noted.
  6. Cardiovascular involvement in ECD is common and may result in conduction disturbances and vavlular dysfunction. Pericardial effusion is common. Cardiovascular disease is the major source of morbidity and mortality in ECD patients.
  7. Pulmonary involvement in patients with ECD, often with pulmonary infiltration in the form of diffuse interlobular septal thickening, may result in shortness of breath. Pleural effusions and / or thickening may occur. Rarely lung cysts have been reported. 

Imaging manifestations of ECD include the following:

  1. Skeletal: symmetric long bone sclerosis, commonly affecting the distal femoral metadiaphysis and tibia is common.  Symmetric radiopharmaceutical uptake on Tc-99m methylene diphosphonate bone scan is typical.
  2. CNS: Pituitary involvement may result in diabetes insipidus or other endocrine disturbances. Meningeal thickening may occur. Ocular involvement may produce retrobulbar lesions that enhance and produce exopthalmos, or a pattern of perineural infiltration may be seen. Eyelid xanthomas may be seen. Mass lesions in the cerebellum, medial temporal lobes, and / or brainstem may be manifestations of CNS ECD.
  3. Cardiovascular: Soft tissue infiltration within the heart, typically the right side, may be seen. Soft tissue infiltration within the atrioventricular groove may occur as well, and periaortic infiltration may occur. This infiltrative tissue may prominently enhance, particularly on MR with late gadolinium enhancement sequences. Pericardial thickening and / or effusion may be encountered. The infiltrative tissue shows metabolic activity at 18FFDG-PET scanning.
  4. Thoracic: Pulmonary involvement occurs in 14-23% of patients with Erdheim-Chester disease, presenting as pleural thickening or effusion. Lung parenchymal involvement typically manifests as smooth interlobular septal thickening and occasionally centrilobular nodules or areas of ground-glass opacity. Less commonly reported pulmonary findings include bronchial dilation, thin-walled cysts, and parenchymal consolidation.
  5. Retroperitoneum: Retroperitoneal involvement occurs in at least 29% of patients, perhaps greater, with Erdheim-Chest disease, typically presenting as perirenal (often referred to as “hairy kidney”) and periaortic soft tissue infiltration. Adrenal enlargement may occur also.

There is no standard treatment for ECD and not all patients require treatment. Treatment is generally recommended for symptomatic patients, asymptomatic patients with CNS involvement or organ dysfunction, and patients with impending organ dysfunction. Treatment primarily consists of medical therapy, such as interferon alpha, glucocorticoids, and / or systemic chemotherapy, with surgery reserved for mechanical complications, such as relief of large pericardial effusions or ureteral obstruction. Radiation therapy is occasionally employed when local palliation is needed.

References

  1. Dion E, Graef C, Haroche J, Renard-Penna R, Cluzel P, Wechsler B, Pitte J-P, Grenier PA. Imaging of thoracoabdominal involvement in Erdheim-Chester disease. AJR Am J Roentgenol 2004;183:1253-60.
  2. Tashjian V, Doppenberg EMR, Lyders E, Broaddus WC, Pavot P, Tye G, Liu AY, Perez J, Ghatak N. Diagnosis of Erdheim-Chester disease by using computerized tomography-guided stereotactic biopsy of a caudate lesion. J Neurosurg 2004; 101:521-7.
  3. Tran T-A, Fabre M, Pariente D, Craiu I, Haroche J, Charlotte F, Eid P, Durrbach A, Taoufik Y, Kone-Paut I. Erdheim-Chester disease in childhood. A challenging diagnosis and treatment. J Pediatr Hematol Oncol 2009; 31:782-6.
  4. Haroche J, Arnaud L, Amoura Z. Erdheim-Chester disease. Curr Opin Rheumatol 2012; 24:53-9.
  5. Arnaud L, Pierre I, Beigelman-Aubry C, et al. Pulmonary involvement in Erdheim-Chester disease: a single-center study of 34 patients and a review of the literature. Arthritis Rheum 2010; 62:3504-12.

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