Adult-onset primary Ewing's sarcoma of the right atrium: a case report

Background: Primary cardiac tumors, which are only detected in 0.001-0.03% of autopsies, are rare. Only 25% of primary cardiac tumors are malignant, of which 95% are sarcomas. Ewing's sarcoma, one of the Ewing's sarcoma of family tumors, is thought to be derived from neural crest cells. While Ewing's sarcoma usually presents in the bone of children, Ewing's sarcoma of cardiac origin is rare, with only a few reports described in the literature. The prognosis is unpredictable because of the scarcity and unestablished treatment. We herein report an extremely rare case of primary cardiac Ewing's sarcoma in the right atrium of a 64-year-old man.

Case presentation: The patient is a 64-year-old Japanese male who was referred to our hospital to treat a floating mass of the right atrium (RA). Although the patient was asymptomatic, we performed an operation to urgently resect the floating mass on the next day of admission due to the risk of pulmonary embolism. The operation was performed under cardiopulmonary bypass and cardiac arrest. We resected the tumor with at least 1.5 cm of the RA wall as a margin. The postoperative pathological diagnosis of the mass was compatible with a primitive neuroectodermal tumor (PNET, a form of Ewing's sarcoma). The cells were positive for CD56, CD99, and Vimentin and negative for S-100 and Desmin. Although no malignant cells were observed in the margin of the resected RA wall and the sarcoma was completely resected, he was transferred to another hospital to receive adjuvant postoperative chemotherapy to improve the prognosis by preventing subclinical micrometastasis.

Conclusions: We experienced an extremely rare case of primary cardiac Ewing's sarcoma in the right atrium of a 64-year-old man, which was successfully resected under cardiac arrest. Although the sarcoma was completely resected, postoperative chemotherapy and long-term follow-up are recommended for patients with primary cardiac sarcoma because of the high rates of metastasis and recurrence.