A case of stacked coin ingestion mistaken for button battery

Button battery ingestion requires emergency endoscopic removal since severe complications, such as esophageal perforation, can develop within 4 hours of the ingestion. Given that guardians do not witness the children’s foreign body ingestion 40% of the time, physicians can only guess what was swallowed based on plain radiography. We report a case of a 45-month-old-boy who visited the emergency department after swallowing an unknown foreign body and whose radiographs showed “circle-within-a-circle appearance” on the anteroposterior view and “step-off appearance” on the lateral view, suggesting button battery ingestion. We conducted emergency endoscopic removal, and found stacked coins mimicking a button battery on the radiographs. The coins were pushed into the stomach and came out through defecation 3 weeks later without further complications. Distinguishing between stacked coins and a button battery through radiography may help avoid unnecessary emergency endoscopy.