(血液内科课件）08.3特发性血小板减少性紫癜

Idiopathic ThrombocytopeniaPurpura （Immune Thrombocytopenia） 特发性血小板减少性紫癜 王 利 重庆医科大学附属第一医院 Outlines Definition Epidemiology Pathogenesis Signs and symptoms Laboratory Findings Diagnosis Treatment Definition ITP is an autoimmune disease with antibodies detectable可检测 against several platelet surface antigens 血小板表面抗原 low platelet count (thrombocytopenia) It causes a characteristic purpuric rash 紫癜性皮疹 and an increased tendency to bleed Epidemiology The incidence going up with the age get older, F:M = 4:1 in adults, male dominant in children and senior 1. Infection Bacteria, virus infection commonly Acute ITP: normally has upper respiratory infection 2-3 weeks before onset Chronic ITP: Infection could be an induction 诱因 Pathogenesis 2. Immunology In approximately 60 percent of cases, antibodies against platelets can be detected. Most often these antibodies are against platelet membrane glycoproteins 血小板膜糖蛋白, and are of the immunoglobulin G (IgG) type. Normal PLT can be destructed in the patient plasma. Immune suppressive drugs is effective to ITP patients. 3. CTL induced platelet destruction The stimulus for auto-antibody production in ITP is probably abnormal T cell activity. Preliminary 初步 findings suggest that these T cells can be influenced by drugs that target B cells, such as rituximab 利妥昔单抗. Symptoms Signs include the spontaneous formation of bruises 淤青 (purpura) , especially on the extremities 四肢, bleeding from the nostrils 鼻孔 and/or gums 牙龈, and menorrhagia 月经过多 (excessive menstrual bleeding 月经出 血), any of which may occur if the platelet count is below 20,000 per l. A very low count (80% auto-curable Recurrent attack to yrs Laboratory Findings 1.Platelet count 2.Bone morrow examination 3.PLT antibody: PA IgG 4.Evans syndrome Blood count（x109/L） platelets 20 mainly 30-80 WBC/RBC Normal Normal Lifespan of PLT BM morphology Laboratory findings Acute ITPChronic ITP 1-6 hrs 1-3 days Hypercellularity No of megakaryocytes normal or increased remarkable Normal of E,G Acute ITP Chronic ITP (Chronic ITP,Wright stain,x200) (Megalokaryocyte, Gimsa stain, x400) Serum PA Ig or PA C3 PA Ig, G or M PAC3 Evans syndrome ITP with AIHA Diagnosis 1. Clinical presentations of bleeding, no physical signs other than bleedings. 2. Low platelet count repeatly 3. Despite the destruction of platelets by splenic 脾的 macrophages, the spleen is normally not enlarged 4. Megakaryocytes in BM normal or increased with maturation 成熟 disorder 5. One of the following five: Corticosteriod effective Splenectomy 脾切除术 effective PA Ig (+) PA C3 (+) Lifespan 寿命 of PLT shortened Classification of acute ITP or chronic ITP Exclusion of secondary thrombocytopenia 血小板减少 (differential diagnosis) 1. Aplastic anemia 再生障碍性贫血 2. Systemic lupus erythematosus 系统性红斑狼疮 3. Drug induced thrombocytopenia 药物性血小板减少症 4. Myelodysplastic syndrome 骨髓增生异常综合征 5. Acute leukemia 急性白血病 Treatment Splenectomy (removal of the spleen) Immunosuppressive agents Cyclosporin 环孢素 Mycophenolate mofetil (MMF) 骁悉 Azathioprine 硫唑嘌呤 Vincristine 长春新碱 Three steps: Corticosteroids Strategy Corticosteroids Thrombopoietin 促血小板生成素受体 receptor agonists Platelet transfusion Except in an emergency, it is not recommended and usually unsuccessful in producing a long-term platelet count increase. Rituximab 利妥昔单