[Squamous cell carcinoma of the lung with high CT number, but without calcification]

Squamous cell carcinoma of the lung was diagnosed in a 64-year-old man. Chest roentgenographic and tomographic examinations did not show areas of high-density in the tumor, but chest CT scan showed diffuse, scattered, high-density nodules in the tumor. Histologic examination did not show calcification, and calcium staining (Kossa method) was negative. Examination of the thin-slice CT, the soft X-ray film, and the resected slice of the lung indicated that the high-density nodules seen in the tumor on the chest CT scan corresponded to markedly fibrotic lesions with severe anthracosis. This case shows that high-density areas on a CT scan may reflect non-calcified lesions.