A Left Atrial Appendage Thrombus Mimicking Atrial Myxoma
A 58-year-old female with a medical history of ≈2 years of chronic atrial fibrillation (on warfarin treatment), previous right mastectomy for invasive ductal carcinoma, and hypertension presented with a hypertensive emergency and mental status changes. Her symptoms resolved with appropriate antihypertensive treatment. The international normalized ratio on presentation was 2.9. During an additional work-up for transient neurological symptoms, transesophageal echocardiography was performed, revealing a 2×2-cm, well-circumscribed, spherical, mobile echodensity within the ostium of the left atrial appendage (LAA), which was attached by an 8-mm–long stalk to the lateral wall of the appendage (Figure 1). Continuous, mild-to-moderate spontaneous echo contrast was noted in the left atrium and LAA, and the peak emptying velocity in the appendage was 10 cm/s (Figure 2). It was unclear whether the mass represented a thrombus or an unusually located atrial myxoma. The patient underwent uncomplicated excision; the operative report describing a “mass floating around the atrium, attached with a very fine pedicle to the left atrial appendage” (Figure 3). Pathological findings disclosed an organizing thrombus (Figure 4). Of note, the entire specimen was examined histologically, because portions of myxoma may look similar to an organizing thrombus. In this case, there was no accumulation of myxoid material, and no stellate cells characteristic of myxoma were found anywhere in the specimen.
This is a case of an unusual macroanatomic appearance of an LAA thrombus with a distinct, long stalk in a patient on therapeutic anticoagulation. The definite differentiation from an atypically located atrial myxoma could only be made with certainty from a very careful histopathological examination.
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