Diagnostic challenges of recurrent left atrial mass: a case report

Background: Differential diagnosis of left atrial (LA) masses is challenging because there is a significant overlap in the epidemiological, clinical, and imaging characteristics. Even some histological features can be similar across different types of cardiac masses. Therefore, continuous case discussion between the clinician and the pathologist is essential for a correct diagnosis. Case summary: We present a case of a patient with a history of cardiac surgery for LA tumour. Histology was compatible with thrombus, although no predisposing causes nor genetic or acquired thrombophilia were identified. After 14 years, the recurrence of LA mass was diagnosed with a routine echocardiography. A review of histological preparations from 2007 with immunohistochemistry techniques not available at that time (calretinin) was consistent with a myxoma. The patient underwent cardiac reoperation with LA mass and interatrial septum excision. Final diagnosis was compatible with a myxoma recurrence. Discussion: Myxoma is the second most frequent benign primary cardiac tumour. Left atrial thrombi can occasionally mimic the typical echocardiographic appearance of a myxoma, and pathological features can sometimes overlap generating diagnostic confusion. Calretinin fixation is useful for differential diagnosis once it is only identified in myxomas but not in thrombi. Any discrepancy between clinical findings and histology should always mandate a review of histological preparations.