Abstract
Pulmonary atypical adenomatous hyperplasia (AAH) is a recognized precursor lesion to pulmonary adenocarcinoma (ADC). We present the case of a 79-year-old ex-smoker in whom transthoracic needle biopsy revealed histological features suggestive of lung ADC. However, surgical resection of the lesion later demonstrated only AAH. This discrepancy likely reflects sampling variability or partial lesion regression, emphasizing the diagnostic challenges posed by small pulmonary nodules. The case highlights the importance of integrating histopathological, radiological, and clinical data, and underscores the critical role of multidisciplinary decision-making in managing preinvasive pulmonary lesions.