BACKGROUND Proteinase 3-antineutrophil cytoplasmic antibody has been reported to be positive in 5-10% of cases of renal injury complicated by infective endocarditis; however, histological findings have rarely been reported for these cases. CASE PRESENTATION A 71-year-old Japanese man with a history of aortic valve replacement developed rapidly progressive renal dysfunction with gross hematuria and proteinuria. Blood analysis showed a high proteinase 3-antineutrophil cytoplasmic antibody (163 IU/ml) titer. Streptococcus species was detected from two separate blood culture bottles. Transesophageal echocardiography detected mitral valve vegetation. Histological evaluation of renal biopsy specimens showed necrosis and cellular crescents in glomeruli without immune complex deposition. The patient met the modified Duke criteria for definitive infective endocarditis. On the basis of these findings, the patient was diagnosed with proteinase 3-antineutrophil cytoplasmic antibody-positive necrotizing crescentic glomerulonephritis complicated by Streptococcus infective endocarditis. His renal disease improved, and his proteinase 3-antineutrophil cytoplasmic antibody titer normalized with antibiotic monotherapy. CONCLUSION Few case reports have described histological findings of proteinase 3-antineutrophil cytoplasmic antibody-positive renal injury complicated with infective endocarditis. We believe that an accumulation of histological findings and treatments is mandatory for establishment of optimal management for proteinase 3-antineutrophil cytoplasmic antibody-positive renal injury complicated with infective endocarditis.

中文翻译：

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蛋白酶3-抗中性粒细胞胞浆抗体阳性坏死性新月形肾小球肾炎并发感染性心内膜炎：一例报告。

背景技术据报道，蛋白酶3-抗中性粒细胞胞浆抗体在并发感染性心内膜炎的肾损伤病例中有5-10％为阳性。然而，很少有关于这些病例的组织学发现的报道。病例介绍一位有主动脉瓣置换史的71岁日本男子迅速发展为进行性肾功能不全，伴有严重血尿和蛋白尿。血液分析显示高蛋白酶3抗中性粒细胞胞浆抗体（163 IU / ml）滴度。从两个单独的血液培养瓶中检测到链球菌。经食道超声心动图检查发现二尖瓣植被。肾活检标本的组织学评估显示，肾小球坏死和细胞新月形没有免疫复合物沉积。该患者符合确定的传染性心内膜炎的修订后的杜克标准。根据这些发现，患者被诊断患有蛋白酶3-抗中性粒细胞胞浆抗体阳性坏死性新月形肾小球肾炎并发链球菌感染性心内膜炎。他的肾脏疾病得到改善，并且他的蛋白酶3-抗中性粒细胞胞浆抗体滴度通过抗生素单一疗法恢复了正常。结论很少有病例报告描述蛋白酶3-抗中性粒细胞胞浆抗体阳性肾损伤并感染性心内膜炎的组织学发现。我们认为组织学发现和治疗方法的积累对于建立蛋白酶3抗中性粒细胞胞浆抗体阳性肾损伤并感染性心内膜炎的最佳管理是必不可少的。