Background-Radiofrequency ablation for atrial fibrillation is becoming widely practiced. Methods and Results-Two patients undergoing circumferential pulmonary vein ablation for atrial fibrillation in different centers developed symptoms compatible with endocarditis 3 to 5 days after the procedure. Their clinical condition deteriorated rapidly, and both suffered multiple gaseous and/or septic embolic events causing cerebral and myocardial damage. One patient survived after emergency cardiac and esophageal surgery; the other died of extensive systemic embolization. An atrio-esophageal fistula was identified in both patients. Conclusions-Atrio-esophageal fistulas can occur after catheter ablation in the posterior wall of the left atrium. This diagnosis should be excluded in any patient with symptoms or signs of endocarditis after left atrial ablation, and expeditious cardiac surgery is critical if the diagnosis is confirmed. Lower power and temperature settings for applications of radiofrequency energy along the posterior left atrial wall may prevent further cases of fistula formation.

Pulmonary lymphoepithelioma-like carcinoma is a rare type of non–small cell lung cancer. The tumor is usually discovered in young, nonsmoking Asian populations. The patients are diagnosed at an earlier stage and have a better prognosis than those with other non–small cell lung cancers. Histologically, the tumor morphology is indistinguishable from undifferentiated carcinoma of the nasopharynx. It is characterized by nests or diffuse sheets of syncytial tumor cells, which show round to oval vesicular nuclei with prominent nucleoli, along with an admixed heavy lymphocytic and plasma cell infiltrate. The presence of Epstein-Barr virus in the tumor cells is crucial for the diagnosis. The differential diagnoses include lymphoepithelioma-like carcinoma from other sites and pulmonary involvement of lymphoma. EGFR mutations and ALK rearrangements are not commonly found in lymphoepithelioma-like carcinoma, in contrast to programmed death ligand-1 expression, which is shown in a majority of cases.

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