We report the case of a patient who had benefited initially from a right middle and lower lobectomy for bronchogenic carcinoma and who bad an extensive radiologic workup in an outside hospital in the early postoperative period. Based on CT scan findings, this patient was referred back with a diagnosis that conveys both medical and medicolegal issues: a gossypiboma (or retained surgical sponge). We describe herein the unexpected operative findings that highlight the difficulty in accurately diagnosing intrathoracic foreign bodies.