Anatomicopathological basis and clinical diagnostic significance of Kerley's A line

Objective: To study anatomic and pathological basis of Kerley's A line, and to evaluate the role of Kerley's A line in differential diagnosis of diffuse lung diseases (DLD). Methods: HRCT scans, gross specimen section(50-100 μm thickness) and histologic section(5-8 μm thickness) were performed and analyzed comparatively on 28 dry lung specimens from the patients with coal worker's pneumoconiosis and occupational exposure history to coal dusts. At the same time, HRCT images of 176 patients with DLD were retrospectively reviewed for the detection of Kerley's A line. Results: Kerley's A lines were seen in 17 of 28 lung specimens on coronal HRCT images. The anatomic basis of Kerley's A line represented the continuity of two or more thickened interlobular septa (14 eases) and incomplete fibrotic septa between segments or subsegments (3 cases). Histologically, the linear opacities represented the deposits of coal dust, fibrosis, edema, inflammation, thickened vessel wall within interlobular septa. Kerley's A lines were present in 11 of 176 patients (6.3%) including interstitial pulmonary edema (5 cases), viral pneumonia (2 cases), lymphangitic carcinomatosis (2 cases), sarcoidosis (1 cases) and pulmonary alveolar proteinosis (1 cases). Conclusion: Kerley's A line has a limited usefulness in the differential diagnosis of DLD because it is seen infrequently and not discermable. (authors)