Plasma cell granulomas are lesions of uncertain histogenesis arising in a variety of locations, most commonly the lung. Treatment for these lesions is complete surgical excision if possible. Unresectable pulmonary lesions respond to oral corticosteroids and radiation therapy. We report the long-term outcome of two unusual pediatric cases of cardiac plasma cell granulomas originating within the right ventricle and posterior aspect of the left ventricle. The limited literature reports advocate surgical resection for this entity, with no discussion of alternative treatment strategies for unresectable lesions. We prospectively evaluated the response to postoperative oral steroid therapy, as complete surgical excision was not possible in either case. Sequential echocardiography demonstrated additional significant reduction in the size of the masses and the patients remain asymptomatic at 9 and 5.5 years follow-up, without evidence of obstruction or recurrence. Oral corticosteroids should be considered as a treatment option for any unresectable plasma cell granuloma.