Pulmonary Atypical Adenomatous Hyperplasia: Diagnostic and Therapeutic Implications.

Lung cancer still remains one of the most common cancers throughout the world, especially in smokers. Adenocarcinoma is now the predominant histological type in many western countries. The etiology of adenocarcinoma is unknown, but evidence suggests that atypical adenomatous hyperplasia (AAH) may act as a precursor lesion. Here we present two case reports of patients diagnosed with AAH on biopsy, highlighting 1) available treatment strategies and 2) AAH's progression to adenocarcinoma. A review of AAH is warranted as little literature is currently available regarding its treatment strategies, especially in light of its role as a precursor to adenocarcinoma. In this review, we will address the following topics: 1. What is the pathophysiology of AAH? 2. What is the natural history of AAH and its risk of malignant transformation? 3. When is surgery recommended? 4. What is the role of stereotactic body radiotherapy (SBRT) in the rare patient who refuses surgery?