Primary pulmonary collision tumor with three components in the underlying interstitial lung disease.

A collision tumor of the lung is relatively rare. We report a case of a 72-year-old man with a collision tumor consisting of three neoplastic components in the underlying interstitial lung disease. Computed tomography showed a parenchymal lesion with an air bronchogram. Transthoracic needle lung biopsy showed chronic inflammation, however, a malignant pulmonary tumor was clinically suspected. The patient underwent a right lower lobectomy with mediastinal lymph node dissection. The histological features of the surgical specimen showed lung cancer with three neoplastic components, which were squamous cell carcinoma, invasive mucinous adenocarcinoma, and invasive non-mucinous adenocarcinoma. To the best of our knowledge, this is the first documentation of a collision lung tumor with three components.