Primary intracardiac leiomyoma arising from cardiomyocyte progenitors at the right ventriculoseptal interface: case report with literature review.

Primary cardiac neoplasms are rare and are usually benign myxomas and rhabdomyomas. Cardiac leiomyomas are usually seen as a part of the spectrum of intravenous leiomyomatosis or benign metastasizing leiomyoma. De novo occurrence of primary intracardiac leiomyomas (PICL) is a rarity. Herein we describe a 14-year-old boy presenting with intermittent dyspnea for 2 years, with a large right ventricular mass suggestive of myxoma on transthoracic echocardiography, without any extracardiac lesions. Histology and immunohistochemistry of the tumor excised under cardiopulmonary bypass confirmed a PICL arising at the cardiomyocyte-smooth muscle septal interface. A review of existing literature highlights an increased incidence in young patients and an overwhelming right ventricular anatomical predilection. Abnormalities in the multipotent cardiac progenitor cells of the second heart field may provide a potential microenvironment for the histogenesis of PICL.