Benign Lung Adenoma Mimicking an Adenocarcinoma with EML4-ALK Gene Fusion

Bronchiolar adenoma is a benign, neoplastic process thought to derive from the bronchiolar epithelium. Particularly in small biopsies, 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 EML4-ALK gene fusion. After being considered for neoadjuvant targeted therapy trials, the patient underwent a lobectomy. On post-operative histologic evaluation, the patient was found to have a benign bronchiolar adenoma.