1、 Polymyositis is an idiopathic inflammatory myopathy that causes symmetrical, proximal muscle weakness; elevated skeletal muscle enzyme levels; and characteristic electromyography (EMG) and muscle biopsy findings (see the images below). Clinically similar to polymyositis, dermatomyositis is an idiop

2、athic, inflammatory myopathy associated with characteristic dermatologic manifestations. Inclusion body myositis is a slowly progressive, idiopathic, inflammatory myopathy with characteristic pathologic findings that is generally found in older males. n 炎性肌病分為特發性和感染性炎性肌病分為特發性和感染性n特發性包括：多發性肌炎、皮肌炎及包含體

3、特發性包括：多發性肌炎、皮肌炎及包含體肌炎等肌炎等n感染性肌炎包括病毒、細菌及寄生蟲感染所感染性肌炎包括病毒、細菌及寄生蟲感染所致的肌炎致的肌炎1. 單純型多發性肌炎單純型多發性肌炎(PM)2. 皮肌炎皮肌炎(DM)3. 兒童多發性肌炎或皮肌炎兒童多發性肌炎或皮肌炎4. 多發性肌炎和皮肌炎合并結締組織病多發性肌炎和皮肌炎合并結締組織病5. 多發性肌炎和皮肌炎合并惡性腫瘤多發性肌炎和皮肌炎合并惡性腫瘤 The major manifestation of polymyositis is inflammation leading to destruction of muscle and incre

4、asing muscular weakness. As the disease progresses, the muscle tissue is replaced by functionless scar tissue. Both have features in common with rhematoid arthritis, lupus, and progressive systemic sclerosis (scleroderma).流行病學流行病學 n性別：女性略多于男性性別：女性略多于男性n年齡：兩個高峰年齡：兩個高峰, 兒童和兒童和4070歲歲n發病率：北美發病率：北美25/10,

5、0000 The causes of polymyositis and dermatomyositis are unknown. It appears that abnormal immunological factors are responsible for at least part of inflammatory attack against muscle tissue. The symptoms of muscular weakness usually wax and wane, but in some instances, the disease may progress rapi

6、dly. The disease may affect persons of any age, but the peak incidence is in the fifth and sixth decades of life. Women are affected twice as commonly as men. An increased association of myositis has been found with human leukocyte antigen (HLA) haplotypes A1, B8, and DR3, which also increase the ri

7、sk for autoimmune diseases. Environmental triggers, especially infectious agents, have been suggested as etiologic agents. These include the following: Coxsackievirus B1 HIV HTLV-1 Hepatitis B Influenza Echovirus Adenovirusl 病毒感染：如感冒病毒感染可引起輕型的肌炎，病毒感染：如感冒病毒感染可引起輕型的肌炎，HIV(+)，HTLV-I感染者常伴感染者常伴PM，但未分離出病毒

8、，但未分離出病毒和和 測出升高的抗病毒抗體。測出升高的抗病毒抗體。l 免疫：免疫：PM主要細胞免疫主要細胞免疫, 抗原性質不清；抗原性質不清；DM主要體液免疫，肌肉小血管壁可見免疫復合物主要體液免疫，肌肉小血管壁可見免疫復合物IgG、IgM和補體和補體C3等沉積。等沉積。l 該病常合并膠原血管病該病常合并膠原血管病, 如如Crolone氏病氏病, SLE, 結結節性肉芽腫節性肉芽腫, 類風濕類風濕, 重癥肌無力等重癥肌無力等Muscle Weakness: Muscle Weakness: Muscles of the shoulder, arms, pelvis, and thighs ar

9、e the most frequent targets, but the reasons are unknown. As the disease spreads, other muscles may become involved. For example, the diaphragm and chest wall muscles, which are needed for breathing, may be attacked. The pharyngeal muscles, which are needed for swallowing, may be weakened to the poi

10、nt that swallowing solid foods becomes impossible. Heart muscle is another potential target.1隱襲、逐漸進展、幾周或幾個月達高峰；隱襲、逐漸進展、幾周或幾個月達高峰；2近端肌肉無力近端肌肉無力3頸部肌肉無力：抬頭困難頸部肌肉無力：抬頭困難, 伸肌較屈肌受累重伸肌較屈肌受累重4球部肌肉：吞咽困難球部肌肉：吞咽困難(約約50%), 構音障礙少見構音障礙少見5肌肉疼痛占肌肉疼痛占65%，晚期遠端肌肉可有輕度萎縮，晚期遠端肌肉可有輕度萎縮6合并其它結締組織病可伴有其它癥狀合并其它結締組織病可伴有其它癥狀7DM臨

11、床有皮膚受累的表現，肌痛較明顯臨床有皮膚受累的表現，肌痛較明顯840歲后發病者歲后發病者10%可能伴有惡性腫瘤可能伴有惡性腫瘤Goetz: Textbook of Clinical Neurology, 2nd ed., Copyright 2003 Elsevier NormalPolyphasicMyopathicGoetz: Textbook of Clinical Neurology, 2nd ed., 2003 Elsevier RestingInterference patternFigure 2: Histological findings in polymyositis and

12、 dermatomyositisA, B: Depletion of capillaries in dermatomyositis (A) with dilatation of the lumen of the remaining capillaries, compared with a normal muscle (B).C: Perifascular atrophy in dermatomyositis. D: Endomysial inflammation in polymyositis and inclusion-body myositis with lymphocytic cells

13、 invading healthyfibres. E: The MHC-I/CD8 complex in polymyositis and inclusion-body myositis. MHC-I (green) is upregulated on all the muscle fibres, and CD8-positiveT cells (orange) that also express MHC-I, invade the fibres.l 血生化：血生化：CK等等, ESR異常異常, 免疫球蛋白免疫球蛋白，部分部分RF(+), 恢復期可正常；恢復期可正常；l 24小時尿肌酸增加小時

14、尿肌酸增加l EMG：肌源性損害：肌源性損害l 肌肉活檢肌肉活檢Figure and caption from American College of Rheumatology slide collectionMRI of thighs showing increased signal in the quadriceps muscles bilaterally consistent with inflammatory myositis. Histopathology of polymyositis showing endomysial mononuclear inflammatory infi

15、ltrate and muscle fiber necrosis. l PM：肌纖維斑片狀壞死和再生：肌纖維斑片狀壞死和再生, 血管周圍有血管周圍有淋巴細胞浸潤淋巴細胞浸潤(75%); 組織化學證實為組織化學證實為CD8, T-淋淋 巴細胞巴細胞l DM：肌束膜結締組織炎性細胞浸潤，束周：肌束膜結締組織炎性細胞浸潤，束周肌纖維萎縮。該病原發的病理改變在血管肌纖維萎縮。該病原發的病理改變在血管1. 病史及臨床表現病史及臨床表現2. 血清肌肉酶譜測定血清肌肉酶譜測定3. EMG提示肌源性損害提示肌源性損害4. 肌肉活檢肌肉活檢: 典型的病理改變典型的病理改變 Treatment may invol

16、ve using a corticosteroid drug, although their effectiveness is less predictable in these disorders than in some other inflammatory diseases. As a result, many rheumatologists turn to one of the cytotoxic drugs (agents that destroy abnormal cells) in conjunction with the corticosteroids, in an attem

17、pt to suppress muscle inflammation and retard the destructive process. Usually by combining the two classes of drugs, lower and safer doses of both can be used thereby avoiding some of the more serious side- effects that might be produced when either is used alone in higher doses. 1. 腎上腺皮質激素治療腎上腺皮質激

18、素治療: 強的松強的松6080mg 或或 氫考氫考 200300 mg 或地或地塞米松塞米松 1020 mg 靜脈點滴靜脈點滴2周后改為強的周后改為強的松口服癥狀好轉后漸減量；松口服癥狀好轉后漸減量；3個月內減至維個月內減至維持量持量520mg/天天, 維持維持25年。年。2. 其它免疫抑制劑其它免疫抑制劑 依米蘭依米蘭 100200mg 1/天天 Cyclophosphamide 50100mg/day Methotroxate 3060mg /week *注意血相注意血相, 肝功能等肝功能等3. 免疫球蛋白靜脈滴注，免疫球蛋白靜脈滴注，0.4g/（kg.d）4. 血漿交換血漿交換In mo

19、st patients, polymyositis responds well to treatment, although residual weakness occurs in approximately 30% of patients. Osteoporosis, a common complication of long-term corticosteroid therapy, may cause significant morbidity. Poor prognostic factors include the following:Advanced ageFemale sexAfri

20、can American raceInterstitial lung diseasePresence of anti-Jo-1 (lung disease) and anti-SRP antibodies (severe muscle disease, cardiac involvement)Associated malignancyDelayed or inadequate treatmentDysphagia, dysphoniaCardiac and pulmonary involvementComplications of polymyositis may include the follow