Hamartoma of mature cardiomyocytes in right atrium: A case report and literature review

RATIONALE: Tumors in the heart are rare. Myxomas, rhabdomyomas, and fibromas are the most common benign cardiac tumors. Hamartoma of mature cardiomyocytes (HMCM) is another benign cardiac tumor, are very rare and have only been reported in a few literatures. PATIENT CONCERNS: We report a case of 41-year-old male who suffered short of breath for 3 years, and lower limbs edema for 2 years. DIAGNOSES: Transthoracic echocardiogram (TTE) and cardiac magnetic resonance (CMR) showed a large amount of pericardial effusion and confirmed a mass of 18 × 14 mm on the superior vena cava near the outer edge of right atrium. The patient was first diagnosed as pleural mesothelioma. Surgery was performed to relieve the symptoms and confirm diagnoses. However, during surgery, we found the right atrium is apparently thicken with rough and uneven surface. Histology of right atrium mass indicated it as hamartoma of mature cardiomyocytes. INTERVENTION: We resected the thicken atrial wall completely, reconstructed right atrium with bovine pericardial patch, and resected the pericardium. OUTCOMES: Patient was discharged 9 days after surgery, and remained asymptomatic during 9 months follow up. LESSONS: Hamartoma of mature cardomyocytes is a rare benign cardiac tumor. There were 26 cases reported until now. The conclusive diagnosis depends on pathological sections. For patients with symptoms, surgery is an effective treatment for HMCM.