Lung cancer diagnosing scar-like lesions on initial computed tomography images

The purpose of this study was to evaluate lung cancers appearing as scar-like lesions on initial CT images. From 1997 to 2008 we retrospectively reviewed 39 patients with lung cancer in whom scar-like lesions were detected on initial CT images. We studied follow-up CT images and analyzed their development. The pathological diagnosis was confirmed by surgical resection in all cases. We evaluated the initial CT findings and the clinicopathological characteristics in these cases. There were 29 men and 10 women, whose mean age was 68.4 years. Brinkmann index was 696 (mean), tumor doubling time was 322.2 days (mean). There were findings of emphysema, fibrosis, or old inflammatory lesions in the lung fields on initial CT images in 26 cases, while 13 had no significant findings. Scar-like lesions appeared as thin or irregular shapes and background lung field findings. There were 29 adenocarcinomas, of which 3 were bronchioloalveolar carcinomas (non-invasive carcinoma). The 5-year survival rate for the entire group was 57.4%. Lung cancers appearing as scar-like lesions on initial CT images tended to occur more often in men, smokers and those with background abnormal lung findings. They tended to have a short tumor doubling time. Some cases of invasive carcinoma had poor outcome. Although it is difficult to diagnose these lung cancers on initial CT images, a careful follow-up can result in a better prognosis. (author)