AB1118 OPEN MUSCLE BIOPSY AS A SAFE AND USEFUL MEANS OF DIAGNOSING VASCULITIS: A SINGLE-CENTER EXPERIENCE OF 210 BIOPSY CASES

Abstract

Background:We previously reported the utility of open muscle biopsies in diagnosing vasculitis [1]. The number of open muscle biopsies performed at our department has increased to over 200. The purpose of the present study was to evaluate the diagnostic utility of vasculitis and the safety of the open muscle biopsies.Objectives:To clarify the diagnostic utility of vasculitis and the safety profile of the open muscle biopsy.Methods:We retrospectively examined all cases of open muscle biopsy performed between May 2012 and June 2018 in our department. The biopsy results, the presence or absence of adverse events, and blood test data at the time of the biopsy were extracted from the patients’ electronic medical records.Results:Between May 2012 and June 2018, 210 open muscle biopsies were performed, 120 of which were done for vasculitis diagnosis. Diagnostic histopathological findings were obtained in 42 of the 120 cases (35%). The definitive diagnosis in these cases was microscopic polyangiitis (30 cases), eosinophilic granulomatosis with polyangiitis (seven cases), granulomatosis with polyangiitis (one case), polyarteritis nodosa (three cases), and other vasculitis (one case). In 57 cases with myeloperoxidase-anti-neutrophil cytoplasmic antibody (MPO-ANCA) ≥ 10 U/ml, 31 cases (54.3%) showed histopathology of vasculitis. In six cases with protainase-3-ANCA (PR3-ANCA) ≥ 10 U/ml, histopathology of vasculitis was found in one case (16.7%).In all 210 open muscle biopsy cases, complications included minor wound dehiscence (11 cases) and small subcutaneous hematoma (six cases), which were able to be managed by local treatment. Albumin was significantly lower in the patients with wound dehiscence (mean 3.2 vs 2.7, p = 0.049)Serious complications included anaphylaxis due to local anesthesia (one case), compartment syndrome due to hematoma (one case), hematoma requiring surgical removal (one case), and arterial hemorrhage requiring surgical intervention (one case). The patients in the latter three hemorrhagic cases were receiving antiplatelet drugs.Conclusion:An open muscle biopsy is useful for diagnosing vasculitis, especially for MPO-ANCA-positive anca-associated vasculitis. Its safety profile is acceptable. Serious adverse events are rare, but the procedure should be performed carefully when patients are receiving antiplatelet drugs.