We report a 76-year-old male who was admitted due to progressive congestive heart failure lasting several months. An echocardiogram showed a large pericardial effusion with early signs of pericardial tamponade and an irregular surface suggestive of cancer infiltration. The patient was operated, creating a pericardial window and draining 1,200 ml of a brownish yellow fluid with abundant cellularity. Pericardial biopsy showed infiltration by CD68 (+), CD1a (-) and S100 (-) cells. Twenty-eight months earlier, due to fatigue, dyspnea, and a non-specific inflammatory process, an enhanced-contrast-scan showed that aorta was coated with a hypodense tissue that began near the aortic valve and extended until the inferior mesenteric artery, with stenosis of the left subclavian, celiac axis, renal and upper mesenteric arteries. An angioplasty and stent placing was carried out in the last two arteries. Both kidneys had the appearance of "hairy kidneys". A bone scan showed increased uptake in femurs and tibiae and X-ray examination showed osteosclerosis in metaphysis and diaphysis. The diagnosis of Erdheim-Chester disease (non-Langerhans-cell histiocytosis) was made and the patient was treated with steroids and methotrexate.