Diagnostic approach to a cardiac mass: a case report of misdiagnosed cardiac synovial sarcoma

Background Cardiac synovial sarcoma (CSS) is an extremely rare malignant tumour with a poor prognosis. We report the case of a 31-year-old woman who presented with a CSS in the right atrium and was initially misdiagnosed with a tuberculoma. The aim of this article is to focus on the importance of having broad differential diagnoses including rare entities. Case summary A 31-year-old White woman, with a close contact with a relative having pulmonary tuberculosis, presented to the emergency unit with severe dyspnoea. Chest radiography and echocardiography showed a large pericardial effusion with a mass in the right atrium. Pericardiocentesis removed bloody exudative fluid with adenosine desaminase at 17 UI/L and no malignant cells in the cytological study. Cardiac magnetic resonance revealed a tuberculoma of the right atrium. Intraoperatively, the mass was only biopsied because of the local invasion. Histological study concluded to a CSS. The patient died 3 days later. Discussion This case highlights the importance of having broad differential diagnoses including rare entities. Histology was the key investigation for the diagnosis of CSS which has no clinical nor laboratory or imaging pathognomonic signs.