Ground-glass opacities showing an adenoma-to-carcinoma sequence in the lung

We encountered a patient with three left lower lobe pulmonary tumors evident as discrete ground-glass opacities by computed tomography. Pathological diagnoses of the resected lesions included a focus of atypical adenomatous hyperplasia (AAH) and two localized noninvasive bronchioloalveolar carcinomas (BACs) of types A and C according to Noguchi's classification. This case supports the hypothesis of an adenoma-to-carcinoma sequence in the lung, as the coexisting lesions represented sequential adenocarcinoma progression from a precancerous lesion, AAH, to very early-stage adenocarcinoma, noninvasive BAC.