过敏性紫癜2005.3.21.ppt

过敏性紫癜Allergic Purpurawangweihong
一、定义(Definition)
是多种原因引起的一种过敏性血管炎,以皮肤、粘膜出现紫红色瘀点为特征,可伴有关节痛、腹痛及肾脏损害。
二、病因及发病机制(Etiology and Pathogenesis )
病因 1)感染:细菌、病毒、寄生虫等
2)食物:海鲜类、劣质小食品
3) 药物
4) 其他
机制Ⅲ型变态反应
Type 3 (plex Disease) In the blood, antigen and antibodies form plexes. These plexes are deposited in the walls of vessels, especially the small vessels of the skin. Vascular damage results as these plexes plement, platelet aggregation, and lysosomal enzyme release from polymorphs. This reaction is seen in systemic lupus erythematosus and dermatomyositis, microbial infections such as infective endocarditis.
Type 3 (plex Type) In the blood, antigen and antibodies form plexes. These plexes are deposited in the walls of vessels, especially the small vessels of the damage results as these plexes plement, platelet aggregation, and lysosomal enzyme release from polymorphs.
三、临床表现(Clinic Manifestation)
(一)单纯型
1)年龄儿童及青少年
2)前期症状
3)部位多见于双下肢,尤以小腿伸侧居多。
4)皮疹为瘀点、瘀斑,散在或密集,对称分布
5)自觉症状一般无自觉症状
(二)关节型
1)常有前期症状发热、头痛、咽痛、恶心、呕吐等
2)皮疹特点:除紫癜外,还可有红斑、水疱、血疱、甚至坏死
3)关节肿胀、疼痛显著。呈固定性、游走性、以大关节为主,膝关节最易受累,其次肘关节、踝、及腕关节等。
(三)腹型
1)皮损特点:同关节型紫癜
2)腹部症状:最常见的是腹痛,位于脐周和下腹部,伴有恶心、呕吐、食欲不振、便秘、便血、腹泻,严重的肠道出现肠穿孔、肠套叠。