Benign Lung Adenoma Mimicking an Adenocarcinoma With Gene Fusion.

Bronchiolar adenoma is a benign neoplastic process thought to be derived from the bronchiolar epithelium. Particularly in small biopsy specimens, this entity can mimic lung cancer with important implications for management. We report the case of a 33-year-old man with a right upper lobe lung nodule, with initial biopsy identifying an adenocarcinoma with gene fusion. After being considered for neoadjuvant targeted therapy trials, the patient underwent a lobectomy. On postoperative histologic evaluation, the patient was found to have a benign bronchiolar adenoma.