Getting to the heart of the matter in a multisystem disorder
A 59-year-old woman was admitted to the emergency department for asthenia and swollen ankles. 1 week earlier she began to feel tired while walking. On clinical examination, peripheral oedema was found but no other signs suggestive of heart failure. Her blood pressure was 150/70 mm Hg. An electrocardiogram showed junctional bradycardia (35 beats per min): P waves were absent and the QRS complexes were regular and narrow. In her medical history, it was noted that she had recently been treated with ibuprofen and colchicine for acute idiopathic pericarditis: the patient had chest pain and paroxysmal atrial flutter. After this episode she had travelled to the Philippines and had further cardiac problems so was started on digoxin 0·25 mg/day.

Laboratory investigations showed a high digoxin concentration (3·97 ng/mL) and a raised concentration of C-reactive protein (12 mg/L) in her serum. An autoimmune antibody screen was negative and microbiology tests—including serum antibodies for hepatitis A, B, and C, and HIV, QuantiFERON-TB Gold In-Tube test and urine PCR for Mycobacterium tuberculosis, Aspergillus fumigatus serum antigen, and blood cultures for aerobic and anaerobic bacteria—were not positive. A transthoracic echocardiogram showed a severe pericardial effusion with thickening of the myocardium on the roof of the right atrium suggestive of a cardiac mass. An MRI also confirmed an effusion causing cardiac tamponade (figure). Digoxin was stopped and the patient's condition improved immediately. A pericardiocentesis was also done, which drained 800 mL of serous fluid—also negative on microbiological tests and showed no malignant cells.

The cardiac MRI was repeated, and the images showed a thickening of the right atrial roof, interatrial septum, and atrioventricular sulcus. Further investigations—which did not show any metastatic neoplasia—were key in steering us towards a diagnosis of a multisystem disorder—namely, Erdheim–Chester disease. A CT scan and MRI of the abdomen showed bilateral dilatation of the renal pelvises and retroperitoneal fibrosis—known as hairy kidneys. Additionally, the MRI showed periadventitial thickening of the abdominal aorta—yet another pathognomonic sign of Erdheim–Chester disease—known as coated aorta. An endomyocardial biopsy specimen provided histological evidence of the diagnosis, showing an infiltration with non-Langerhans histiocytes: immunohistochemical analysis was positive for CD68 but negative for CD1a and S100. We also found the patient had a mutation of the BRAF gene, specifically BRAFV600E. Soon after admission she became lethargic and confused, so we did an MRI of her brain, which showed a parenchymal lesion of the left trigone of the lateral ventricle. Patient died 4 weeks after admission.

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