The risk of misdiagnosing pulmonary adenocarcinoma as traumatic pseudocyst in a young adult.

A 35-year-old male was transferred because of bruising on the chest. A computed tomography scan revealed a pulmonary pseudocyst. Although the pulmonary pseudocyst remained unchanged it accumulated fluid. Based on our concern regarding hemoptysis, the patient underwent S6 segmentectomy of the right lower lobe. The postoperative pathological examination revealed a cystic lesion, including a white mass on the cystic wall. Unexpectedly, the mass was composed of papillary adenocarcinoma. Acute care surgeons should be alert to the possible presence of tumor in trauma patients. A cystic lesion must be carefully distinguished from a traumatic pulmonary pseudocyst and lung cancer.