Time	Event
2010	Diagnosed with dilated cardiomyopathy.
2012	Abdominal pelvic computed tomography (CT) and diagnostic ureteroscopy were performed. He was diagnosed with idiopathic retroperitoneal fibrosis and bilateral hydronephrosis.
Day 1 (30 December 2020)	Admission due to dyspnoea. Transthoracic echocardiography revealed a large amount of pericardial effusion and an echogenic mass on the right atrial side and atrioventricular groove.
Day 4	Heart magnetic resonance image showed infiltrative mass-like lesions in the right atrial (RA) wall and atrioventricular (AV) groove.
Day 8	Cardiac positron emission tomography–CT showed fluorodeoxyglucose uptake in the RA and AV groove.
Day 9	Pericardial window formation and pericardial biopsy were performed.
	Pathologic results showed only pericardial fibrosis with no specific findings.
Day 14	Whole-body bone scan revealed increased uptake in both distal femurs and proximal tibiae.
Day 16	Cardiac biopsy following median sternotomy.
Day 23	Pathologic report revealed chronic inflammation and fibrosis and CD68 positivity on immunohistochemical staining. In addition, BRAF V600E mutation was detected.
	Finally diagnosed with Erdheim–Chester disease.
1 month later	Referral to the haematology department; chemotherapy with etoposide and dexamethasone started.