Ab0778 histopathologic features and clinical outcomes in patients with eosinophilic granulomatosis with polyangiitis

Background The main histological features of eosinophilic granulomatosis with polyangiitis (EGPA) are tissue eosinophilia (TE), small-vessel vasculitis (SVV), and extravascular granuloma. However, the relationship between these pathological findings and treatment response is not known. Objectives To explore the associations between pathological features of TE or SVV and the clinical parameters and treatment response in EGPA patients. Methods This is a single-center, retrospective, cohort study. Subjects who met the following were included for analysis: 1) those who fulfilled the 1990 ACR criteria and/or the 2012 revised CHCC criteria and/or the ACR/EULAR 2022 criteria, 2) those who were treated for at least 2 years in our hospital since 1/1/2010, 3) those who had undergone tissue biopsy at any site during their initial diagnostic workup. All available slides of biopsies were reviewed by a blinded pathologist expertise with vasculitis. Based on the EULAR recommendations, remission was defined as the absence of vasculitis activity (BVAS=0) with daily doses of prednisolone <=7.5mg after 2 years of treatment and refractory disease was defined as failure to attain remission. Results Among 37 patients diagnosed with EGPA, 30 patients were included. Total 84 biopsies (muscle 36, skin 15, nose 9, colon 8, stomach/duodenum 4, nerve 4, kidney 3, lung 2, heart 1, small intestine 1, and temporal artery 1) were reviewed. SVV, TE, and extravascular granuloma were found in 17 (56.5 %) patients, 16 (53.3 %) patients and 3 (10 %) patients, respectively. (Fig.1) SVV was associated with refractory disease (47.1 % vs 0 %, p=0.04). TE was associated with skin lesions (56.2 % vs 14.3%, p = 0.021) and inversely associated with severe peripheral neuropathy (43.8 % vs 85.8 %, p = 0.021). (Table.1) ANCA was present in 11 (36.7 %) patients. ANCA was not associated with refractory diseases (ANCA positive 36.3% vs ANCA negative 21.1%, p=0.31) Conclusion In EGPA, pathological evidence of SVV may be better predict poor treatment response than ANCA positivity. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests None Declared.