[Lung cancer combined with connective tissue disease-related interstitial lung disease: CT features]

Objective: To investigate the CT features and dynamic changes of new developed lung cancer in patients with connective tissue disease-related interstitial lung disease (CTD-ILD). Methods: A series of chest CT images of 58 CTD-ILD patients during follow-up were collected. The CT features of interstitial lung disease, the initial appearance time of lung cancer, the time of diagnosis of lung cancer, the morphological characteristics (location, shape, size) of lung cancer lesions and the dynamic changes of CT features were analyzed. Results: Among 58 patients, rheumatoid arthritis was the most common (31 cases). Chest CT images showed coexistence of two or more interstitial CT signs. During the follow-up, a total of 59 lung cancer lesions were found. The median time of lung cancer lesion occurred was 289 days. The median delay in diagnosis was 43 days. There were 44 cases of non-small cell lung cancer (including 23 cases of squamous cell carcinoma and 19 cases of adenocarcinoma), 12 cases of small cell lung cancer. Forty-three (72.9%) lesions were located in the lower lobes and 41 (69.5%) lesions were located in the area of pulmonary interstitial fibrosis. According to CT morphological characteristics of lung cancer, nodular type (37 cases), inflammatory consolidation (12 cases) and intra-honeycomb type (10 cases) were identified. Conclusions: The chest CT features of patients with CTD-ILD are complex. New developed lung cancer is easily missed or misdiagnosed in the early stage. Pay attention to the special CT characteristics of CTD-ILD with lung cancer is helpful for early diagnosis.