Abstract 4147632: Unusually Expeditious Expansion of an Atrial Myxoma

Description of the Case Report: A 44-year-old female with a past medical history of unspecified skin cancer presented with exertional dyspnea for 1 day before admission and syncope 7 months before admission. Physical exam was noted for soft low low-pitched diastolic murmur at the cardiac apex, not appreciated on prior exam. Echocardiography revealed a 3.3x4.7 cm pedunculated, homogenous mass in the left atrium obstructing the mitral valve. Serum BNP was measured as 326. An echocardiogram from less than 29 months prior was reviewed and showed no mass in the left atrium. The patient underwent successful surgical resection of the mass. The mass measured approximately 7x6x2 cm. Histologic analysis reported a proliferation of myxoid stroma with cytologically bland spindle cells positive for calretinin, compatible with cardiac myxoma. Following the surgery, the patient experienced resolution of symptoms. Discussion: Atrial myxomas are the most common primary cardiac tumors. They present as mitral valve obstruction, mitral valve regurgitation, arrhythmias, or systemic thromboembolism. They are exceedingly rare with an incidence of 0.5 to 1 case per million individuals annually and typically resected immediately. Therefore, instances with well-documented growth rates are uncommon. In this case, we present an unusually fast-growing myxoma in a woman with shortness of breath and syncope. The reported growth rate of atrial myxomas ranges from 1.3 to 6.9 mm a month. Our patient had a negative echocardiogram less than 2.5 years before her presentation, followed by the development of a 7 x 6 x 2 cm mass. Since the onset is unknown, the precise growth rate of our patient's tumor is unknown but was at least 24 mm/month. It is important to consider myxoma in the differential diagnosis of a woman with new onset murmur and syncopal episode. Furthermore, recognizing the potential for rapid expansion is crucial to assessing the risks versus benefits of myxoma section.