The histopathological lesions of ILAs earlier than the radiological changes

<bold>Aim:</bold> To describe the pathological features ILAs. <bold>Methods:</bold> Patients who were hospitalized for lung lesion resections with chest HRCT scans were identified. The HRCT images were used to identify ILAs and their subcategories according to the Fleischner Society position paper. Patients with a history of ILD, familial ILD, CTD, and with HRCT findings of other lung diseases were excluded. Patient were divided into two groups. The ILAs near lung lesions group and the ILAs distant from the lung lesions group referred to that ILA abnormalities were in the same and different segment of the lesions, representing region with pulmonary parenchymal changes and normal region on HRCT respectively. <bold>Results:</bold> The frequency of pathological changes of ILD (11/24 (45.83%) in the ILAs near lung lesions group vs 7/28 (25.00%) in the ILAs distant from lung lesions group, p = 0.115) as well as the subtype of ILD histologic changes showed no significant difference. In the ILAs near lung lesions group, 4 (16.67%) were UIP, 2 (8.33%) were NSIP, 6 (25.00%) were OP, and 1 (4.17%) were RB-ILD/DIP. And for the ILAs distant from the lung lesions group, the corresponding proportions were 1 (3.57%), 1 (3.57%), 4 (14.29%), and 1 (3.57%), respectively. However, inflammatory infiltration was identified more frequently in the cases of the ILAs near lung lesions group than in the cases of the ILAs distant from lung lesions group (22/24 (91.67%) vs 13/28 (46.43%), p = 0.001). More lymphocytes (18/24 (75.00%) vs 10/28 (35.71%)) and plasmacytes (13/24 (54.17%) vs 2/28 (7.14%)) were found in the ILAs near lung lesions group. <bold>Conclusion:</bold> The histopathological lesions of ILAs may occur earlier than the radiological changes.