Data from: Differential clinicopathological features of EGPA-associated neuropathy with and without ANCA

Objective: To investigate the clinicopathological features of eosinophilic granulomatosis with polyangiitis (EGPA)-associated neuropathy with a focus on the presence or absence of anti-neutrophil cytoplasmic antibodies (ANCAs). Methods: We examined the clinical features and pathological findings of sural nerve biopsy specimens from 82 patients with EGPA-associated neuropathy. Of these patients, 32.9% were myeloperoxidase (MPO)-ANCA-positive, and 67.1% were MPO-ANCA-negative. PR3-ANCA was negative in all of 78 examined patients. Results: Upper-limb symptoms were more frequently reported as initial neuropathic manifestations in the MPO-ANCA-positive group than in the MPO-ANCA-negative group (44.4% vs. 14.6%, p < 0.01). The serum levels of C-reactive protein were significantly higher in the MPO-ANCA-positive group than in the MPO-ANCA-negative group (p < 0.05). Sural nerve biopsy specimens showed findings suggestive of vasculitis (i.e., destruction of vascular structures) in epineurial vessels; these results were more frequently seen in the MPO-ANCA-positive group than in the MPO-ANCA-negative group (p < 0.0001). Conversely, the numbers of eosinophils in the lumen of the epineurial vessels (p < 0.01) and epineurial vessels occluded by intraluminal eosinophils (p < 0.05) were higher in the MPO-ANCA-negative group than in the MPO-ANCA-positive group. Furthermore, the incidence of eosinophil infiltration in the endoneurium was higher in the MPO-ANCA-negative group than in the MPO-ANCA-positive group (p < 0.01). Conclusions: This study suggests that the pathogenesis of EGPA comprises at least two distinct mechanisms: ANCA-associated vasculitis resulting in ischemic effects and inflammation, which is prominent in MPO-ANCA-positive patients, and eosinophil-associated vascular occlusion leading to ischemia and eosinophil-associated tissue damage, which is conspicuous in MPO-ANCA-negative patients.