Abstract
BackgroundThe clinical characteristics of myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) positive granulomatosis with polyangiitis (GPA) remain unclear, as does the difference between MPO-ANCA positive GPA and proteinase 3 (PR3)-ANCA positive GPA, especially with regard to the details of respiratory tract involvement. We investigated the differences in clinical, radiological, and histopathological features between PR3-ANCA positive GPA and MPO-ANCA positive GPA.MethodsWe retrospectively reviewed 16 patients who were newly diagnosed with GPA between December 2000 and July 2014. One patient, who was positive for both PR3-ANCA and MPO-ANCA, was excluded. Our review was based on the European Medicine Agency (EMA) algorithm.ResultsFifty-six percent of GPA patients were positive for PR3-ANCA, 38 % for MPO-ANCA, and the remaining 6 % for both. The MPO-ANCA positive group included a greater number of females (67 %). There were no statistically significant differences in laboratory data, symptoms and signs, Birmingham Vasculitis Activity Score, or CT findings between the two groups. As for upper respiratory tract involvement, the most common manifestation was paranasal sinusitis, whereas lung nodules were most common as the lower respiratory tract involvement in both groups. Although the combination therapy with prednisone and cyclophosphamide was the most common initial treatment in both groups, the relapse rate in MPO-ANCA positive cases was lower than that of PR3-ANCA positive cases (17 % and 56 %, respectively).ConclusionA high prevalence of MPO-ANCA positive GPA was noted. No significant differences in clinico-radiological findings were observed except for the prevalence of relapse between the PR3-ANCA positive cases and MPO-ANCA positive cases, suggesting that the type of ANCA may be of little help in the diagnosis of GPA. Examination for granulomatous findings in the respiratory tract is important, even in MPO-ANCA positive cases. There is a need to accumulate more cases and conduct a further investigation in the future.
Highlights
The clinical characteristics of myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) positive granulomatosis with polyangiitis (GPA) remain unclear, as does the difference between MPO-ANCA positive GPA and proteinase 3 (PR3)-ANCA positive GPA, especially with regard to the details of respiratory tract involvement
In 1990, the classification criterion, established with the combination of clinical characteristics and pathological characteristics, was reported by the American College of Rheumatology (ACR) [2], and this was followed by the Chapel Hill Consensus Conference (CHCC), wherein the classification was established from a pathological perspective [3]
It is estimated that the onset of GPA involves a genetic background with additional environmental factors (Staphylococcus aureus infection [6], silica, etc.) that leads to the production of ANCA, resulting in the excessive activation of neutrophils and causing vascular disorders [7]
Summary
The clinical characteristics of myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) positive granulomatosis with polyangiitis (GPA) remain unclear, as does the difference between MPO-ANCA positive GPA and proteinase 3 (PR3)-ANCA positive GPA, especially with regard to the details of respiratory tract involvement. In 2007, the European Medicine Agency (EMA) proposed a multi-stage classification algorithm of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and classic polyarteritis nodosa (PN) using ACR classification criteria, CHCC classification, and surrogate markers for vasculitis and ANCA, with the aim of applying the classification in epidemiological researches [4]. It is estimated that the onset of GPA involves a genetic background with additional environmental factors (Staphylococcus aureus infection [6], silica, etc.) that leads to the production of ANCA, resulting in the excessive activation of neutrophils and causing vascular disorders [7]. It is thought that neutrophils are activated under the presence of PR3ANCA, and subsequently, inflammatory cytokine, reactive oxygen, and protease are released from the neutrophils fixated onto the vascular wall, resulting in the onset of vasculitis and granulomatous inflammation [8]
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