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

Abstract

This study aimed to compare thin-section CT images from sarcoidosis patients who had either normal or elevated serum KL-6 levels. 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 U ml(-1), mean 305.7 U ml(-1)) and 26 sarcoidosis patients (7 male, 19 female; aged 19-75 years, mean 54.3 years) with elevated KL-6 levels (541-2940 U ml(-1), mean 802.4 U ml(-1)). Two chest radiologists, unaware of KL-6 levels, retrospectively and independently interpreted CT images for parenchymal abnormalities, enlarged lymph nodes and pleural effusion. 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. These results suggest that serum KL-6 levels may be a useful marker for indicating the severity of parenchymal sarcoidosis.