Objective This study aimed to analyze the chest CT features and clinical manifestations in patients with IgG4-related lung disease (IgG4-RLD).

Methods We retrospectively analyzed the clinical data of 61 patients diagnosed with IgG4-RLD at Beijing Friendship Hospital (affiliated with Capital Medical University) from January 2020 to December 2023. Based on allergy status, patients were categorized into allergic (n=30) and non-allergic (n=31) groups. Clinical data included demographic characteristics, clinical symptoms, comorbidities, laboratory examinations, and imaging examinations.

Results The male-to-female ratio was 2.4∶1, with 93.4% of patients aged ≥ 45 years. Among these, 49.2% had allergic diseases, with a higher proportion of females in the allergy group compared to the non-allergic group (43.3% vs. 16.1%, P < 0.05). However, age distribution showed no statistically significant differences. Respiratory symptoms occurred in only 11.5% of patients during the disease course, indicating low incidence without significant intergroup differences. The main chest CT abnormality was hilar and/or mediastinal lymphadenopathy (63.9%), followed by interlobular septal thickening (34.4%). Other findings included bronchovascular bundle thickening, ground-glass opacities, and pleural thickening, each at 21.3%. Two or more imaging abnormalities were observed in 60.7% of patients, with no statistically significant differences between groups. Extrapulmonary organ involvement distribution revealed a higher incidence of salivary glands (93.3% vs. 71%), eye muscles and lacrimal glands (86.7% vs. 54.8%), skin (40% vs. 0%), and sinus (30% vs. 6.5%) in the allergic group, while pancreatic involvement was more common in the non-allergic group (74.2% vs. 40%). Additionally, based on the number of affected organs (≤2, 3~5, or >5), cases were divided into three groups. The highest incidence occurred in the allergic group with more than five affected organs (60% vs. 29%, all P<0.05). Laboratory investigations demonstrated no significant differences in IgG4 levels and eosinophil counts between groups.

Conclusion The main chest CT indicator of IgG4-RLD is hilar or mediastinal lymphadenopathy. Chest CT features do not correlate with allergies. Isolated lung involvement is rare, and allergic patients are more likely to experience extrapulmonary organ involvement than non-allergic patients.