Symptomatic mitral stenosis caused by a left atrial mass as the first sign of metastasis of a malignant tumor is extremely rare and frequently associated with poor prognosis. We report a case of a 59-year-old man with a history of grade 3 malignant fibrous histiocytoma on his left tigh treated by limb-sparing surgery 17 months earlier, who was admitted with 10-days of worsening dyspnea. Imaging revealed a left atrial mass protruding through the mitral valve that resulted in severe mitral stenosis. Biopsy confirmed metastasis of malignant fibrous histiocytoma
