Unravelling a hidden case of Erdheim-Chester disease in persistent pericardial effusion

Abstract Introduction Erdheim-Chester disease (ECD) is a rare non-Langerhans cell, non-familial multisystemic histiocytosis, with widespread manifestations and of highly variable severity. Case presentation We present the case of a 68-year-old man with a history of polyvascular disease admitted for the re-evaluation of persistent pericardial effusion despite treatment with standard anti-inflammatory therapy. A cardiac magnetic resonance (CMR) was performed, confirming the circumferential pericardial fluid. In addition, a process sheathing the visceral pericardium in relation to the right and left atrium and the inferior vena cava was observed, raising the suspicion of ECD. The positron emission tomography (PET) scan confirmed increased fixation at the level of the lesion and at the level of the kidneys. A renal biopsy was performed, confirming the disease and showing the presence of BRAF mutation. Re-evaluation after one year of BRAF inhibitors targeted therapy by PET scan showed the disappearance of hypermetabolism and hyperfixation in the entire body, together with the disappearance of the pericardial effusion. An atrial mass of similar dimension was observed during control CMR with absence of intramyocardial fibrosis and a significant regression of inflammatory and perfusion signs on CMR. Conclusion This report presents a rare case of ECD initially diagnosed through cardiac involvement, highlighting the importance of considering this entity in atypical cardiovascular presentations and the value of imaging in early diagnosis.