[Early image of squamous cell carcinoma in the peripheral lung field on high-resolution CT scan]

A 65-year-old man presented with the shadow of an abnormal nodule in the left lower lung field in a chest radiograph. We diagnosed this as an old inflammatory change because prior chest radiographs had shown the same nodule in the same lung field. However, a high-resolution CT scan showed a hazy ground-glass opacity (GGO) near the nodule. Two years later, this GGO changed into a small nodule. After a CT-guided transbronchial lung biopsy performed by ultra-thin fiberoptic bronchoscopy, we diagnosed this nodule as squamous cell carcinoma. We speculated that the hazy GGO detected in the peripheral lung field on high-resolution CT two years before diagnosis may have been an early image of squamous cell carcinoma.