BACKGROUND Atypical adenomatous hyperplasia (AAH) of the lung is a putative precursor lesion of adenocarcinoma, according to many immunohistochemical and genetical studies, but few clinicopathological studies on a large number of cases have been reported. The aim of this study was to clarify the clinicopathological characteristics of lung cancer patients with AAH lesions.

RESULTS A total of 311 AAH lesions were found in 118 (23.2%) of the 508 cases. AAH lesions were detected in 121 of 572 lobes examined, usually in both upper lobes, and occurred most frequently in patients with adenocarcinoma (OR 2.97; 95% CI 1.82 to 4.85). AAH lesions were more frequently detected in patients with multiple primary carcinomas than in those with a single carcinoma (OR 3.06; 95% CI 1.56 to 6.00). The presence of AAH lesions was not significantly correlated with sex, age, smoking status, familial history of malignancy, or preceding malignancy. Patients with multiple AAH lesions were found to have a significantly higher frequency of preceding malignancies.

CONCLUSIONS The present study highlights the clinicopathological characteristics of AAH lesions, showing them to be significantly associated with both adenocarcinoma and multiple primary carcinoma of the lung and suggesting common factors in the histogenesis of multiple AAH lesions and preceding malignancy.