Collision of lymphoepithelioma-like carcinoma and adenocarcinoma of the lung: a case report.

We report a rare case of collision of lymphoepithelioma-like carcinoma (LELC) and adenocarcinoma (AC) in the lung. A 59-year-old woman had a history of fever and cough. A mass was found by X-ray in the left upper lung. Magnetic resonance imaging (MRI) shows a dumbbell-like mass in the fore and tongue segment of the left upper lung with irregular spiculate margin. Positron emission tomography/computed tomography (PET/CT) (18F-FDG) shows strong concentration of radioactivity (SUVmax 6.9-12.3 cm) in the lung mass only. The patient subsequently underwent resection of left upper lung and associated hilar lymph nodes. Histological examination revealed it was a collision carcinoma comprising LELC and AC. The hilar lymph nodes were tumuor free. The immunoreactions, Epstein-Barr early RNA in situ hybridization and molecular analyses, such as EGFR mutation, c-Met, anaplastic lymphoma kinase were different in both tumuor components, indicating they derived from different cell origin. This rare case was discussed.