To describe the clinical characteristics of patients with autoimmune diseases associated interstitial lung diseases (AID-ILD) initially presented with idiopathic pulmonary fibrosis (IPF) in a tertiary Chinese hospital.

We conducted a retrospective analysis of 14 patients diagnosed with AID-ILD during the IPF follow-up between January 2016 and December 2021. Among the 14 enrolled AID-ILD cases, there were 13 males and 1 female, (69.71±9.07) years old (range from 55 y to 87 y).

Detailed clinical consultation and further laboratory analysis were performed during the follow-up when the IPF patients showed exaggerated dyspnea (7 cases), fever of unknown causes (6 cases), microscopic hematuria (5 cases), arthralgia and swelling (4 cases), arthralgia (2 cases), morning stiffness (2 cases) and renal failure (2 cases). Finally, 6 patients showed positive MPO-ANCA, one patient showed positive PR3-ANCA and 7 patients showed positive anti-CCP. During the IPF periods, 7 patients had received antifibrotic agents and 5 patients had been prescribed with N-acetylcysteine, and 1 patient had received antifibrotic agents after N-acetylcysteine. Among them, no medication was prescribed for one IPF patient. After they were diagnosed with AID-ILD, glucocorticoids and/or immunosuppressants were added for 13 of them. Thirteen of cases improved or stable after these treatments, but one didn′t show significant changes.

AID-UIP, especially ANCA-UIP, AAV-UIP or RA-UIP should be considered when the IPF patients showed fever of unknown origin, microscopic hematuria and/or arthritis related symptoms. They might benefit from the add-on glucocorticoids and/or immunosuppressants.

Usual interstitial pneumonia; Idiopathic pulmonary fibrosis; Rheumatoid arthritis; ANCA associated vasculitis