Focal ground-glass opacity detected by low-dose helical CT

Objective: Focal ground-glass opacity (GGO) has been detected increasingly by low-close helical CT. Although focal GGO suggests in situ neoplastic lesion in the peripheral lung, it remains controversial how to manage these lesions. The purpose of this study was to evaluate the pathologic and radiologic characteristics of focal GGO in order to develop a standard of treatment for these lesions. Patients: Forty-three patients with persistent focal GGO less than or equal to 2 cm in size from January 1998 to September 2000 were studied. Thoracoscopic lung biopsy was performed consecutively for persistent focal GGO following a several-month observation period (mean, 3.7 months). Results: The histologic diagnoses were bronchioloalveolar carcinoma (BAC) in 23 patients, adenocarcinoma with mixed subtypes in 11 patients, and atypical adenomatous hyperplasia (AAH) in 9 patients. None of 34 carcinoma patients had lymph node involvement. All of 17 lesions greater than or equal to 1 cm in size were malignant. GGO with solid components on high-resolution CT were highly associated with adenocarcinoma (malignant rate, 93.3%). Conclusions: Persistent focal GGO after observation for several months was a finding of early adenocarcinoma or its precursor. Especially, lesions greater than or equal to 1 cm in size or GGO with solid component were significant signs of malignancy. We concluded lung biopsy should be attempted for persistent focal GGO.