A case of cerebral embolism due to left atrial myxoma useful in transesophageal echocardiography and pathological findings of retrieved thrombus

A 75-year-old man with no apparent risk factors for cardioembolic stroke was transported presenting with left hemispatial neglect and left complete hemiplegia. MRI revealed a new cerebral infarction in the right middle cerebral artery territory with diffusion-weighted imaging and fluid-attenuated inversion recovery mismatch. The occluded vessel was the right middle cerebral artery (M1 segment). Intravenous rt-PA and mechanical thrombectomy were performed. Pathology of the retrieved thrombus revealed a foreign body granuloma and lipomatous lesion with cholesterol with some calretinin-positive cells. Electrocardiography and transthoracic echocardiography (TTE) showed no abnormalities however, a 4.2mm high-intensity homogeneous plaque in aortic arch and a 14 × 17mm mobile tumor with a stalk were observed in transesophageal echocardiography (TEE). Pathological examination of the tumor revealed a stroma rich in vascular axes and hyaline collagen fibers, with retention of Alcian blue-positive mucinous matrix, leading to a diagnosis of left atrial myxoma. Aortogenic embolism or embolism due to left atrial myxoma was considered. However, since the retrieved thrombus contained calretinin-positive cells, left atrial myxoma was diagnosed as the cause of the embolism. TTE may fail to detect tumors due to factors such as small size. Therefore, TEE is considered necessary in cases of unexplained embolism.