Abstract
Hamartoma of mature cardiac myocytes (HMCM) is a rare, benign cardiac tumor. We report a case of a 19-year-old female with an atypical presentation, including significant weight loss and abnormal electrocardiogram. A transthoracic echocardiogram (TTE) revealed a mass causing left ventricular outflow tract (LVOT) obstruction, confirmed by cardiac magnetic resonance (CMR) imaging showing a 5 x 3 cm mass contiguous with the right ventricular free wall and exhibiting heterogeneous, diffuse late gadolinium enhancement. The patient subsequently underwent sternotomy for surgical biopsy and septal myectomy, with histology of the mass being consistent with HMCM. The patient remained asymptomatic during her 6-month follow-up.