An uncommon case of a rapidly growing intracardiac mass.

Cardiac myxomas typically demonstrate slow growth rates, with rapid enlargement raising suspicion for malignancy. We present a 77-year-old male with a history of non-Hodgkin lymphoma who developed symptomatic atrial fibrillation. Transthoracic echocardiography revealed a left atrial mass measuring 2.5 cm that was absent six months earlier, suggesting a growth rate of approximately 5 mm/month. Multimodality imaging including transesophageal echocardiography, cardiac CT, and MRI showed features suggestive of myxoma but could not definitively exclude lymphoma recurrence given the patient's oncological history and atypical growth pattern. Thoracoscopic resection was successfully performed. Histopathology confirmed a cardiac myxoma with central necrosis-a rare finding occurring in less than 3% of cases-which likely contributed to the unusually rapid growth. This case highlights the diagnostic value of multimodality imaging and the importance of multidisciplinary decision-making in managing complex cardiac masses.