Comparison of pulmonary thin section CT findings and serum KL-6 levels in patients with sarcoidosis

Objective: This study aimed to compare thin-section CT images from sarcoidosis patients who had either normal or elevated serum KL-6 levels. Methods: 101 patients with sarcoidosis who underwent thin-section CT examinations of the chest and serum KL-6 measurements between December 2003 and November 2008 were retrospectively identified. The study group comprised 75 sarcoidosis patients (23 male, 52 female; aged 19–82 years, mean 54.1 years) with normal KL-6 levels (152–499 Uml –1 , mean 305.7 Uml –1 ) and 26 sarcoidosis patients (7 male, 19 female; aged 19–75 years, mean 54.3 years) with elevated KL-6 levels (541–2940 Uml –1 , mean 802.4 Uml –1 ). Two chest radiologists, unaware of KL-6 levels, retrospectively and independently interpreted CT images for parenchymal abnormalities, enlarged lymph nodes and pleural effusion. Results: CT findings in sarcoidosis patients consisted mainly of lymph node enlargement (70/75 with normal KL-6 levels and 21/26 with elevated KL-6 levels), followed by nodules (50 and 25 with normal and elevated levels, respectively) and bronchial wall thickening (25 and 21 with normal and elevated levels, respectively). Ground-glass opacity, nodules, interlobular septal thickening, traction bronchiectasis, architectural distortion and bronchial wall thickening were significantly more frequent in patients with elevated KL-6 levels than those with normal levels (p,0.001, p,0.005, p,0.001, p,0.001, p,0.001 and p,0.001, respectively). By comparison, there was no significant difference in frequency of lymph node enlargement between the two groups. Conclusion: These results suggest that serum KL-6 levels may be a useful marker for indicating the severity of parenchymal sarcoidosis.