Primary undifferentiated high-grade pleomorphic cardiac sarcoma in the left atrium with atypical presentation.

A woman in her 60s had 4 months of malaise, fatigue, dyspnoea, night sweats and grade 3 clubbing. She had a pansystolic murmur and signs of congestive heart failure. Multimodal imaging with a transthoracic echocardiogram, transoesophageal echocardiogram and CT was carried out to diagnose and reconstruct the mass for surgical planning. A 2×2.8 cm circular dense mass was found in the left atrium with vegetations on the mitral valve. Positron emission tomography and cardiac MRI confirmed the mass's hypermetabolic activity and malignant features. Mitral valve replacement and surgical resection were performed. She was diagnosed with grade 3 undifferentiated cardiac sarcoma and referred to the sarcoma multidisciplinary team for further management given sarcoma's rarity and complexity. The poor prognosis of sarcoma was evident as her symptoms recurred 2 months postoperatively.