过敏性紫癜 (简称 AP)是以毛细血管炎为主要病变的变态反应性疾病 ,发病年龄以学龄期儿童最常见。典型病例诊断不难 ,但腹痛、关节肿痛、血尿及皮肤肿块伴疼痛出现在紫癜之前常易造成误诊。现将 1 991— 1 999年误诊的 2 0例分析如下。1　临床资料　　男 1 2例 ,女 8例 ,年龄 2 Allergic purpura (referred to as AP) is the main disease with capillary vasculitis allergic diseases, the age of onset to school-age children is the most common. Typical case diagnosis is not difficult, but abdominal pain, joint swelling and pain, hematuria and skin mass with pain in the purpura often cause misdiagnosis. The 20 cases misdiagnosed from 1991 to 1999 are analyzed as follows. A clinical data of male 1 2 cases, 8 females, age 2