Deceptive appearance of a rapidly growing left atrial myxoid sarcoma with pancreatic metastasis.

The third case reported in the literature of a left atrial neoplasm characterized by a very deceptive, low grade cellular component at its early stage of growth, so as to be diagnosed as a myxoma is presented. Two months after surgical excision, regrowth of the mass occurred, producing a pancreatic mass also. The new atrial mass was excised; a left atrial myxoid sarcoma and a pancreatic metastasis were diagnosed. One week later the atrial sarcoma grew again. This time surgery was contraindicated and the patient underwent chemotherapy with a satisfactory control of the sarcoma growth. The myxoid sarcoma may present with the deceptive appearance of a myxoma in their early stages. Therefore, patients who have undergone surgical removal of a myxoma should have a close follow-up to monitor unexpected malignant turnover.