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.