AAH refers to a single row of non-invasive atypical epithelial cells lining the alveolar wall in a mild to moderate atypical cellular restrictive hyperplasia not associated with the primary lung cancer lesion, which can lead to focal lesions in the peripheral alveoli when the respiratory bronchioles are involved. It causes focal lesions in the peripheral alveoli, usually ≤5 mm, without interstitial inflammation or fibrotic changes. In the early 1990s, it was suggested that this disease may be a precursor to adenocarcinoma of the lung and is the initial stage in the progression of adenoma-alveolar carcinoma of the bronchi and invasive adenocarcinoma. AAH has no obvious clinical symptoms or signs and is detected by surgical resection of lung cancer specimens or chest CT examination. AAH is more commonly seen in adenocarcinoma of the lung, especially in multiple adenocarcinomas, and imaging of multiple adenocarcinomas is the only way to detect “suspicious” AAH. X-ray chest radiographs are less likely to detect AAH, and high-resolution CT of the chest shows small, round-like lesions with clear borders and faint to moderate density, with uniform gross or frosted glass shadows (GGO), GGO is not a specific imaging feature of AAH. 30% of GGO surgical specimens are benign lesions, 10%-77% are AAH, 50% are bronchoalveolar carcinoma, and 10%-25% are invasive adenocarcinoma. In the case of lung cancer, in addition to GGO manifestations, there are other lung cancer features, such as burrs, pleural traction, which may have solid granules and may have a bloom, mulberry, or insect-like morphology. Treatment and prognosis of AAH AAH is usually found in surgically resected specimens of lung cancer, which may be protected from lung cancer. A detailed series of chest CTs should be read before surgery for lung adenocarcinoma, noting the presence of GGO or fine nodules in areas other than the cancer. The scope of AAH resection should be small rather than large, and for GGO or fine nodules that cannot be reached by the intraoperative investigation, long-term postoperative follow-up should be performed to dynamically observe the changes. In recent years, the development of small incision surgery and thoracoscopic surgery has reduced surgical trauma. For small lesions near the chest wall that can be reached by minimally invasive surgery, if lung cancer cannot be excluded by examination, treatment can be decided accordingly, which may be beneficial to improve the prognosis. Although there is no clear conclusion as to whether isolated AAH that is not lung cancer should be surgically resected, minimally invasive surgery is worthwhile if the patient has high risk factors for lung cancer and cancer cannot be excluded.