Role of KL-6 in evaluating the disease severity of rheumatoid lung disease: comparison with HRCT.
OBJECTIVE
To determine the role of KL-6 (Krebs von den Lungen-6) in evaluating the disease severity of pulmonary lesions in rheumatoid arthritis (RA) compared with high resolution computed tomography (HRCT) findings.


METHODS
Fifty serum KL-6 levels and HRCT images were prospectively obtained from 47 RA patients. Eight HRCT findings were classified into five grades. Patients were also divided into two groups according to the KL-6 threshold level and HRCT findings were evaluated.


RESULTS
There was a positive correlation between the serum KL-6 level and the total CT score (r = 0.83). Reticular opacity most closely related to the serum KL-6 levels (r = 0.84). In the high KL-6 group (n = 10), the average CTscore was markedly increased (64.6 points) and severe honeycombing expanded into the whole lung. One case revealed diffuse ground glass opacity. In 12 of 40 cases in the normal KL-6 group, CT scores mildly increased compared with the other cases (over 20 points). The predominant finding of these cases could be classified into four types: (1) narrow spread honeycombing; (2) subtle fibrosis; (3) airway diseases; and (4) dense consolidation.


CONCLUSIONS
KL-6 is a useful marker to detect severe RA lung disease. It is also useful to distinguish non-fibrosis from fibrosis predominant cases. However, it sometimes could not detect early stage RA lung disease.
Kinoshita
Fumiko
F
Department of Radiology, Faculty of Medicine, Tottori University, Yonago, Tottori 683-8504, Japan. tamachan@mg.0038.net
Hamano
Hidefumi
H
Harada
Hiromi
H
Kinoshita
Toshibumi
T
Igishi
Tadashi
T
Hagino
Hiroshi
H
Ogawa
Toshihide
T
D000328:Adult; D000368:Aged; D000941:Antigens / Q000097:blood*; D000951:Antigens, Neoplasm; D001172:Arthritis, Rheumatoid / Q000150:complications*; D015415:Biomarkers / Q000097:blood; D005260:Female; D006023:Glycoproteins / Q000097:blood*; D006801:Humans; D008171:Lung Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000209:etiology; D017563:Lung Diseases, Interstitial / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000209:etiology; D008297:Male; D008875:Middle Aged; D018396:Mucin-1; D009077:Mucins; D011446:Prospective Studies; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed / Q000379:methods
D000941:Antigens; D000951:Antigens, Neoplasm; D015415:Biomarkers; D006023:Glycoproteins; C060192:MUC1 protein, human; D018396:Mucin-1; D009077:Mucins