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.