The inadvertent loss of surgical sponges remains a dreadful hazard of surgery. We report the case of a patient with a medical history of myotonic dystrophy type 1 who had received a right upper lobectomy for the treatment of a stage IIA (pT1N1M0) well differentiated neuroendocrine carcinoma. In the early postoperative period, aspiration of gastric contents occurred and the patient underwent endotracheal intubation and mechanical ventilation. A follow-up multi-detector computed tomography (MDCT) scan of the chest showed a complex mass in interlobar position with an internal radiopaque serpiginous thread of metallic density which was assumed to represent a retained surgical sponge. Upon surgical exploration, no retained foreign body was found and a zone of recent hemorrhagic infarction, bordered by the line of the mechanical staples used to complete the minor fissure, was removed from the middle lobe. When evaluating patients suspected of having a retained surgical sponge, thoracic surgeons and radiologists should be aware of this potential source of confusion.