Lhote F, Cohen P, Généreau T, Gayraud M, Guillevin L
Service de Médecine Interne, Hôpital Delafontaine, Saint-Denis.
Ann Med Interne (Paris). 1996;147(3):165-77.
Recently individualized from polyarteritis nodosa (PAN), microscopic polyangiitis (MPA) is defined as a systemic necrotizing vasculitis that clinically and histologically affects small-sized vessels (ie, capillaries, venules or arterioles) without granulomata and is associated with focal segmental necrotizing glomerulonephritis. Males are more frequently affected than females and the average age of onset is about 50 years old. Most patients experience some systemic symptoms before diagnosis of vasculitis. Clinically, renal involvement is the major feature of MPA and is characterized by rapidly progressive glomerulonephritis (RPGN). Most of the patient have renal impairment at admission and renal function deteriorates rapidly without treatment. Lung involvement is also common. Lung hemorrhage is observed in 12 to 29% of the patients with MPA and is an important contributory factor to morbidity and mortality. Some patients with small-vessel lung vasculitis may present clinical, radiologic and functional findings consistent with an interstitial process mimicking idiopathic pulmonary fibrosis. Others clinical features are similar to those observed in PAN. Musculoskeletal involvement (myalgias, arthralgias and arthritis) are present in 65 to 72% of the patients. Cutaneous lesions (purpura, splinter hemorrhages) are found in 44 to 58% of the patients. Gastrointestinal symptoms are characterized by abdominal pain (32 to 58%) and digestive tract bleeding (29%). Peripheral neuropathy is found in only 14 to 36% of the cases, thus occurring less frequently than in PAN. Ocular manifestations and ear, nose and throat lesions are commonly seen, more frequently than in PAN. Non-specific laboratory tests reflect the systemic inflammatory nature. Almost all patients are negative for hepatitis B virus (HBV) surface antigen. Renal insufficiency with creatininemia > 120 microns/l is present in the majority of patients. Antineutrophil cytoplasm antibodies (ANCA) are found in 75% of MPA patients and the majority of these ANCA detected are perinuclear-staining anti-myeloperoxidase ANCA, although anti-proteinase 3 has also be detected. Microaneurysms, commonly present in PAN, are rarely seen on at visceral angiograms. MPA is part of a spectrum of systemic vasculitides. Differentiation between PAN and MPA should be based on clinical manifestations (especially lung and kidney involvement), biologic signs (ANCA, HBV or HCV infection) and angiographic data. The therapeutic strategies for treatment of PAN and MPA do not differ extensively. Prognosis of systemic vasculitides have been transformed by corticosteroids that are the basis of the treatment. Immunosuppressive drugs, especially cyclophosphamide, also contribute to a better prognosis. Considering the high frequency of renal involvement in MPA, most of the patients should considered as having factors or poor prognosis and the high number of relapses that can occur in patients with MPA could justify prolonged steroid administration or immunosuppressive treatment.
显微镜下多血管炎（MPA）最近从结节性多动脉炎（PAN）中独立出来，被定义为一种系统性坏死性血管炎，在临床和组织学上累及小血管（即毛细血管、小静脉或小动脉），无肉芽肿形成，且与局灶节段性坏死性肾小球肾炎相关。男性比女性更易受累，平均发病年龄约为50岁。大多数患者在血管炎诊断前会出现一些全身症状。临床上，肾脏受累是MPA的主要特征，表现为快速进展性肾小球肾炎（RPGN）。大多数患者入院时就有肾功能损害，若不治疗，肾功能会迅速恶化。肺部受累也很常见。12%至29%的MPA患者会出现肺出血，这是发病和死亡的重要因素。一些小血管性肺血管炎患者可能出现与特发性肺纤维化相似的间质性病变相关的临床、放射学和功能表现。其他临床特征与PAN中观察到的相似。65%至72%的患者有肌肉骨骼受累（肌痛、关节痛和关节炎）。44%至58%的患者有皮肤病变（紫癜、裂片样出血）。胃肠道症状以腹痛（32%至58%）和消化道出血（29%）为特征。仅14%至36%的病例出现周围神经病变，因此其发生率低于PAN。眼部表现以及耳鼻喉病变很常见，比PAN更频繁。非特异性实验室检查反映了全身炎症性质。几乎所有患者的乙型肝炎病毒（HBV）表面抗原均为阴性。大多数患者存在肌酐血症>120微摩尔/升的肾功能不全。75%的MPA患者可检测到抗中性粒细胞胞浆抗体（ANCA），其中大多数检测到的ANCA为核周型抗髓过氧化物酶ANCA，不过也检测到了抗蛋白酶3。PAN中常见的微动脉瘤在内脏血管造影中很少见。MPA是系统性血管炎谱系的一部分。PAN和MPA的鉴别应基于临床表现（尤其是肺部和肾脏受累情况）、生物学指标（ANCA、HBV或HCV感染）以及血管造影数据。PAN和MPA的治疗策略差异不大。皮质类固醇是治疗的基础，改变了系统性血管炎的预后。免疫抑制药物，尤其是环磷酰胺，也有助于改善预后。鉴于MPA中肾脏受累的频率较高，大多数患者应被视为具有预后不良因素，且MPA患者可能出现的高复发率可能说明需要延长类固醇给药或进行免疫抑制治疗。
