1.Overview
Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of diseases with prominent muscle involvement of the proximal extremities. Among them, polymyositis (PM) and dermatomyositis (DM) are the most common. The incidence of PM/I)M in China is not very clear, and the incidence reported abroad is about (0.6~1)/10,000, more women than men, and DM is more common than PM.
2.Clinical manifestations
2.1 Symptoms and signs
PM is mainly seen in adults, but rare in children.DM can be seen in both adults and children.PM/DM often has a subacute onset. PM/DM is often accompanied by systemic manifestations, such as weakness, anorexia, loss of body mass and fever, etc.
2.1.1 Manifestations of skeletal muscle involvement
Symmetrical proximal muscle weakness is the characteristic manifestation of PM/DM. About 50% of patients may have myalgia or myalgia at the same time.J: When the proximal limb muscles are involved, there may be difficulty in raising the arm. Inability to comb hair and dress. When the proximal muscles of the lower extremities are involved, it is often difficult to walk up stairs and steps. Distal muscle weakness is uncommon in patients with PM/DM. However, patients may have varying degrees of distal muscle weakness throughout the course of the disease. As the disease progresses. Myasthenia gravis may occur. About half of the patients have cervical flexor weakness, which is manifested by difficulty in raising the head when lying down. The head is often tilted back. Involvement of the orbicularis oculi and facial muscles is rare. This helps to differentiate it from myasthenia gravis.
2.1.2 Manifestations of skin involvement
In addition to muscle involvement, DM has characteristic manifestations of skin involvement. Skin lesions may precede muscle involvement. The common skin lesions in DM include.
① periorbital rash (heliotrope rash): This is the characteristic skin lesion of DM. The incidence is about 60% to 80%. It appears as an edematous purplish rash on the upper eyelid or periorbital area, either unilaterally or bilaterally. It is aggravated by light exposure. The rash also appears on both cheeks, the bridge of the nose, the neck, the V-shaped area of the forehead, and the back of the shoulders (called the shawl sign).
②Gottron’s sign: It appears on the extensor surfaces of joints. Especially the red or purplish papules on the metacarpophalangeal joints, finger joints or elbow joints, with irregular margins or fused patches, often accompanied by skin atrophy, capillary dilation and hyperpigmentation or hypopigmentation, occasionally with skin breakdown, the incidence is about 80%. These lesions can also be found on the extensor surfaces of the knee joints and the inner ankles. The surface is often covered with scales or local edema: this is another characteristic skin damage of DM.
(③) Perineural lesions: capillary dilated erythema or petechiae can be seen at the nail root crease, irregular thickening of the nail crease and nail bed, local hyperpigmentation or depigmentation.
④”Mechanic’s hand”: The skin on the palm and side of the fingers is hyperkeratotic, cracked and rough, similar to the hands of skilled workers who have been engaged in manual work for a long time, hence the name “mechanic’s hand”. Thickened, rough and hyperkeratotic skin on the heel may also be present. These patients are often seropositive for anti-Mi-2 antibodies.
⑤ Other skin mucosal changes: cutaneous vasculitis and lipofuscinosis are also more common skin lesions in DM; in addition, there can be Raynaud’s phenomenon of the fingers, finger ulcers and oral mucosal erythema. Some patients can also appear muscle sclerosis, subcutaneous nodules or subcutaneous calcification and other changes.
2.1.3 Manifestations of extracutaneous and skeletal muscle involvement
2.1.3.1 Pulmonary involvement: interstitial pneumonia, pulmonary fibrosis, and pleurisy are the most frequent pulmonary manifestations of PM/DM and can appear at any time during the course of the disease. The manifestations are chest tightness, shortness of breath, cough, sputum, dyspnea and cyanosis. A small number of patients have few nasty pleural effusions and large pleural effusions are rare. Weakness of the laryngeal muscles may cause dysphonia and hoarseness, etc. Diaphragmatic involvement may manifest as superficial breathing, dyspnea or cause acute respiratory insufficiency. Pulmonary involvement is one of the important factors affecting the prognosis of PM/DM.
2.1.3.2 Gastrointestinal tract involvement: PM/DM involving the pharynx and upper esophagus transverse muscle is more common, manifesting as dysphagia, choking and coughing when drinking water, and liquid flowing out of the nostrils. Weak and dilated peristalsis of the lower esophagus and small intestine can cause acid reflux, esophagitis, dysphagia, epigastric distension and absorption disorders, etc. These symptoms are similar to the digestive tract involvement in scleroderma.
2.1.3.3 Cardiac involvement: The incidence of PM/DM cardiac involvement is 6%-75%, but those with obvious clinical symptoms are rare, and the most common manifestations are cardiac arrhythmia and conduction block. Less common severe muscular manifestations are congestive heart failure and pericardial tamponade, which is one of the important causes of patient death.
2.1.3.4 Renal involvement: A small number of PM/DM may show renal involvement, such as proteinuria, hematuria, and tubular urine, and rare fulminant PM may show rhabdomyolysis, myoglobinuria, and renal failure.
2.1.3.5 Joint manifestations: some PM/DM ding H{present arthralgia or arthritis manifestations, usually seen in the early stage of the disease, can manifest as RA-like joint symptoms, but generally more common than light castor stack syndrome patients with joint symptoms. Joint symptoms are also relatively more common in children with DM.
2.2 Auxiliary examinations
2.2.1 General examination
Patients may have mild anemia and leukocytosis. About 50% of PM patients can have normal erythrocyte sedimentation rate (ESR) and C-reactive protein, and only 20% of PM patients have ESR>50mm/1h in active phase, so the levels of ESR and C-reactive protein are not parallel to the degree of PM/DM disease activity. Serum immunoglobulins, immune complexes, and alpha2 and gamma globulins may be elevated. Complement C3 and C4 may be decreased: blood myoglobin levels are increased in patients with acute myositis, and the level of serum myoglobin can estimate the acute activity of the disease, increasing in addition to castor and decreasing in remission. When there is acute extensive muscle damage, patients may develop myoglobinuria and also hematuria, proteinuria, and tubuluria, suggesting renal damage.
2.2.2 Myozyme profile examination
PM/DM patients in the acute phase of serum muscle enzymes, such as creatine phosphokinase (CK), aldolase, aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH), etc., of which CK is the most commonly used clinically, its changes are most sensitive to myositis, and the degree of elevation parallels the degree of muscle damage. serum CK values in PM/DM can be as high as 50 times the upper limit of normal, but rarely exceed the upper limit of normal. 50 times the upper limit of normal, but rarely exceeds 100 times the upper limit of normal. Myoenzymatic changes precede changes in muscle strength and electromyography, with muscle strength often lagging behind myoenzymatic changes by 3-10 weeks, and myoenzymes preceding changes in muscle strength in relapses. In a few patients, CK remains elevated when muscle strength is completely normalized, which may be related to the “leakage” of myocyte membrane caused by the lesion.
In contrast, CK levels can be normal in a few patients during the active phase, which is more common in DM than PM. patients with PM/DM with normal CK should be carefully differential diagnosed, as CK levels are always elevated during the active phase of myositis, especially in PM patients, otherwise the accuracy of the diagnosis is questionable.
2.2.3 Autoantibodies
2.2.3.1 Myositis-specific antibodies: antibodies in PM/DM can be divided into 2 major categories: myositis-specific autoantibodies (MSAs) and myositis-associated antibodies, which mainly include anti-aminoacyl-tRNA synthetase (ARS) antibodies, anti-signaling antibodies, and anti-signaling antibodies. MSAs mainly include anti-aminoacyl-tRNA synthetase (ARS) antibodies, anti-signal recognition particle (SRP) antibodies, and anti-Mi-2 antibodies.
There are more than 10 anti-ARS antibodies against histidine (Jo-1), threonine, alanine, aminoacetyl and other aminoacyl synthetases, among which anti-Jo-1 antibodies are the most common and clinically significant. The positive rate of anti-Jo-1 antibodies in PM/DM is 10% to 30%. Patients with positive anti-ARS antibodies often have clinical manifestations such as fever, interstitial lung lesions, arthritis, Raynaud’s phenomenon and “mechanic’s hand” and are called “antisynthetase syndrome (ASS)”. This is called “antisynthetase syndrome”. However, some ASS do not present with all of the above symptoms, and some ASS may not present with myositis.
Anti-SRP antibodies are mainly found in PM, with a positivity rate of about 4-5%. It was previously thought that anti-SRP antibody-positive patients often develop in the fall and winter months and present with acute episodes of severe myositis, often with cardiac involvement. They have no interstitial lung lesions or arthritis, respond poorly to hormone and immunosuppressive therapy, and have a poor prognosis. However, a number of recent studies have demonstrated that anti-SRP positive patients do not have significant seasonal onset and cardiac involvement, and that the clinical presentation is heterogeneous. They may have interstitial lung lesions and may also be seen in patients with DM, and their prognosis and survival rates are not significantly different (or even better) than those of anti-SRP-negative patients. Therefore, the exact clinical characteristics and prognosis of anti-SRP-positive patients need to be analyzed in a larger sample.
However, the pathological features of anti-SRP-positive patients are often consistent, showing marked myofiber necrosis, but often without infiltration of inflammatory cells, and myocytes expressing major histocompatibility complex (MHC) I molecules, a presentation very similar to immune-mediated necrotizing myositis. Anti-SRP may also be occasionally seen in patients with non-IIM atrophic myopathy. Anti-Mi-2 antibodies are positive in about 4% to 20% of PM/DM patients. It is mostly seen in DM and less frequently in PM, so it is thought that it is a DM-specific antibody and is associated with rash in DM patients.
2.2.3.2 Myositis-associated antibodies: PM/DM also has some non-specific myositis-phase inflammatory antibodies, and anti-nuclear antibodies (ANA) can be found in about 60% to 80% of patients. About 20% of patients can be positive for rheumatoid flash (RF), but with low titers. Non-specific antibodies against antigens such as myoglobin, myosin, troponin or promyosin may also be detected in the serum of some patients. Anti-Scl-70 antibodies are often found in DM patients with systemic sclerosis (SSc): anti-SSA and anti-SSB antibodies are found in patients with dry syndrome (SS) or systemic lupus erythematosus (SLE); anti-PM-Scl antibodies are found in 10% of patients with myositis, half of whom have a combination of scleroderma. In addition, anti-Ku antibodies may be present in about l/3 of patients.
2.2.4 Electromyography
Electromyography is a sensitive but non-specific indicator for PM/DM. 90% of active patients may present with EMG abnormalities, and about 50% of patients may exhibit the typical triad of changes.
(i) small polyphasic motor potentials of short duration.
(ii) Fibrillation potentials, sinusoidal waves, mostly in the acute progressive or active phase, which often disappear after hormonal treatment;
(iii) interpolated human irritation and abnormal high-frequency discharges, which may be due to diffuse damage of the myofibrillar membrane.
Another 10% to 15% of patients may have no significant abnormalities on EMG, and a few patients have extensive muscle weakness even though the EMG examination only suggests abnormalities in the paraspinal muscles. In addition. Patients with advanced disease may show neurogenic damage, showing a mixed phase of neurogenic and myogenic damage.
2.2.5 Muscle pathology
2.2.5.1 Pathological features of PM: muscle biopsy pathology is an important basis for the diagnosis and differential diagnosis of PM/DM. plain hematoxylin-eosin (HE) staining of PM muscle biopsy specimens often shows muscle fiber size variation, degeneration, necrosis and regeneration, and infiltration of inflammatory cells. This presentation is not specific and can be seen in muscle lesions of various causes.
It cannot be used to differentiate PM from other myopathies. Immunohistochemical examination shows that myocytes express MHC Ⅰ molecules and the infiltrating inflammatory cells are mainly CD8+ T cells, which are distributed in a multifocal pattern around and within the myofibers, which is a more characteristic manifestation of PM and the most important pathological criterion for the diagnosis of PM. This is because it can be used to distinguish drug-related, metabolic and other non-IIM myopathies. These non-IIM myopathies mainly show infiltration of macrophages rather than CD8+ T cells, and myocytes do not express MHC Ⅰ molecules.
2.2.5.2 Pathologic features of DM: The muscle pathology of DM is characterized by an inflammatory distribution located around the vessels or in and around the fascicular septum, but not within the muscle fascicles. The infiltrating inflammatory cells are predominantly B cells and CD4+ T cells. There is a clear difference from PM. However, myofibrillar expression of MHC Ⅰ molecules was also significantly upregulated. Intramyocardial capillary density was reduced but the remaining capillary lumen was significantly dilated. Myofibrillar injury and necrosis usually involves part of the myofascicle or perifascicle and leads to perifascicular atrophy. Perifascicular atrophy is the characteristic manifestation of DM, and some scholars believe that if the muscle biopsy shows the manifestation of perifascicular atrophy, DM can be diagnosed even if no obvious inflammatory manifestation is seen.
3.Diagnostic points
3.1 Diagnostic criteria: At present, most doctors still use the diagnostic criteria suggested by Bohan/Peter in 1975 (referred to as B/P criteria) for the diagnosis of PM/I)M, see Table 1.
Table l Diagnostic criteria of PM/DM suggested by Bohan/Peter
1. Symmetrical proximal muscle weakness manifested by symmetrical weakness of the scapular girdle muscles and anterior cervical extensor muscles lasting for weeks to months. With or without esophageal or respiratory tract muscle involvement.
2, muscle biopsy abnormalities: muscle fiber degeneration, necrosis, cell phagocytosis, regeneration, basophilic degeneration, nuclear membrane enlargement, nucleus accumbens, atrophy of perifascial structures, variable fiber size, with inflammatory exudation.
3.Elevated serum myoenzymes: elevated serum myoenzymes, such as CK, aldolase, ALT, AST and LDH.
4, EMG shows myogenic damage: EMG has triadic changes: i.e. short time frame, small polyphasic motor potentials; fibrillation potentials, sinusoidal waves; insertional provocation and abnormal high frequency discharges.
5. Typical skin lesions.
(i) periorbital rash: lid is lavender, periorbital edema;
②Gottron’s sign: erythematous scaly rash on the dorsal surface of the metacarpophalangeal and proximal interphalangeal joints;
③Erythematous rash on the knees, elbows, ankles, face, and upper body
Judgment criteria: Confirmation of PM should meet all l to 4 criteria
Judgment criteria: confirmed PM eagle should meet any 3 of 1 to 4 criteria; suspected PM should meet any 2 of 1 to 4 criteria: confirmed DM should meet Article 5 plus any 3 of 1 to 4; proposed DM should meet Article 5 and any 2 of l to 4; suspected DM should meet Article 5 and any 1 of 1 to 4 criteria.
The B/P criteria can lead to overdiagnosis of PM, and it cannot differentiate PM from other inflammatory myopathies such as inclusion body myositis (IBM). Therefore, the European Center for Neuromuscular Diseases and the American Muscle Research Collaborative (ENMC) proposed an alternative diagnostic criterion for IIM classification in 2004, which is shown in Table 2. The major differences between this criterion and the B/P criterion are.
(i) IIM was classified into five categories: PM, DM, inclusion body myositis (IBM), nonspecitlc myositis (NSM) and immune-mediated necrotizing myopathy (IMNM), in which NSM and IMNM were defined explicitly for the first time.
②A clearer diagnostic criteria were proposed for amyopathic dermatomyositis (ADM). However, it should be noted that ADM is not fixed, and some patients may develop typical DM over time. in addition, AMD may present with severe interstitial lung lesions and esophageal lesions, and may also be associated with tumorigenic disease.
Table 2 Diagnostic criteria for IIM classification recommended by the International Myopathy Collaborative Group
Diagnostic requirements
Diagnostic criteria
1.Clinical criteria
Contains the following criteria.
A, often >18 years of age seizures, non-specific myositis and DM can occur in childhood
B, subacute or insidious seizures
C, muscle weakness: symmetrical proximal > distal. Cervical flexors > cervical extensors
D. Typical rash of DM: periorbital edematous purple rash; Gottron’s sign. V-shaped sign in the neck, shawl sign
Exclusion criteria.
A. Clinical manifestation of I of IBM: asymmetric muscle weakness. Wrist/hand flexors are as weak or worse than deltoids, knee extension and/or ankle dorsiflexion are as weak or worse than hip flexion
B, ocular muscle weakness, idiopathic dysphonia, neck extension > neck flexion weakness
C. Drug toxic myopathy, endocrine disorders (hyperthyroidism, hyperparathyroidism, hypothyroidism). Amyloidosis . Familial muscular dystrophy disease or proximal motor neuropathy
2.Elevated serum CK level
3.Other laboratory criteria
A. Myoelectric perimetry examination
Include the following criteria: (I) increased insertional and spontaneous activity of fibrillation potentials, positive phase waves or compound repetitive discharges; (II) morphometric analysis showing the presence of short duration, small amplitude polyphasic movements
unit action potentials (MUAPs);
Exclusion criteria: (I) myotonic discharges suggesting proximal myotonic dystrophy or other conductive channelopathies; (II) morphometric analysis showing long duration, large amplitude polyphasic MUAPs; (III) reduced type of MUAPs recruited by forceful contractions
B. Magnetic resonance imaging (MRI)
STIR shows diffuse or lamellar signal enhancement (edema) within the muscle tissue
C, myositis-specific antibodies
4, muscle biopsy criteria
A, inflammatory cells (T cells) wrapped and infiltrated into the non-necrotic muscle endothelium
B, CD8+ T cells wrapping around non-necrotic muscle endothelium but infiltrating into non-necrotic muscle endothelium is uncertain, or obvious MHC-Ⅰ molecular expression
C, perifascicular atrophy
D, Small vessel membrane attack complex (MAC) deposition. Or capillary density is reduced, or light microscopy shows tubular inclusion bodies in endothelial cells, or perivascular fiber MHC-Ⅰ expression
E. Perivascular hemorrhage. Inflammatory cell infiltration in the myocardium
F. Scattered CD8+ T-cell infiltrates in the endothelium, but it is not sure whether the infiltrates into the muscle fibers or not.
G, massive myofiber necrosis is prominent, but inflammatory cells are not obvious or only a few are scattered in the perivascular area, and the infiltration of myofibrillar membrane is not obvious.
H, MAC deposition in small vessels or EM see pipe stem-like capillaries, but whether there are tubular inclusion bodies in endothelial cells is not certain
I, Possible IBM manifestation: rimmed vacuoles, fragmented red fibers, negative cytochrome peroxidase staining
J, MAC deposition in the endothelium of non-necrotic myofibers, and other indications of immunopathology related to myotonic dystrophy
Polymyositis (PM)
To confirm the diagnosis of PM.
1, All clinical criteria are met. Except for rash
2, elevated serum CK
3, muscle biopsy including A, except C, D, H, I
Diagnostic PM (Drobable PM): 1.
1.Meets all clinical criteria. Excluding rash
2, elevated serum CK
3, other laboratory criteria in the l, 3
4, muscle biopsy criteria including B, except C, D, H, I
Dermatomyositis (DM)
Confirmed diagnosis of DM.
1, meet all clinical criteria
2, muscle biopsy including C
Proposed diagnosis of DM.
1, all clinical criteria are met
2, muscle biopsy criteria including D or E, or elevated CK, or 1/3 of other laboratory indicators
Without myopathic dermatomyositis.
1, DM typical rash: periorbital rash or edema, Gottron’s sign, V-sign, cape sign
2. Skin biopsy demonstrating reduced capillary density. MAC deposition along the dermal-epidermal junction, peri-MAC with numerous keratinized cells
3, no objective muscle weakness
4, CK is normal
5.EMG is normal
6.If muscle biopsy is done, there is no typical DM manifestation
Suspicious dermatomyositis without dermatitis
(Possible DM sine dermatitis).
1, meet all clinical criteria. Except for the rash
2, elevated serum CK
3, l/3 of other laboratory indicators
4, biopsy criteria in line with C or D
Non-specific myositis.
1.Meets all clinical criteria, except rash
2.Serum CK is elevated
3, 1/3 of other laboratory indicators
4, muscle biopsy including E or F. and except all other manifestations
Immune-mediated necrotizing myopathy.
1, meets all clinical criteria, except rash
2, Elevated serum CK
3, 1/3 of other laboratory indicators
4, muscle biopsy criteria including G, except all other manifestations
3.2 Differential diagnosis: Multiple diseases can cause skin and muscle lesions. DM is generally not difficult to diagnose if there are typical manifestations of skin rash and muscle weakness. The most easily misdiagnosed clinically is PM, which needs to be differentiated from many types of myopathies: the main types of myopathies that should be differentiated in PM include: infection-related myopathy, IBM, thyroid-related myopathy, metabolic myopathy, drug-related myopathy, hormonal myopathy, myotonic dystrophy, eosinophilic myositis, and tumor-related myopathy.
4.Treatment plan and principles
PM/DM is a heterogeneous group of diseases. The clinical manifestations are diverse and vary from person to person, and the treatment plan should follow the principle of individualization.
4.1 Glucocorticoids
To date, glucocorticoids are still the first choice for PM and DM. However, there is no uniform standard for the use of glucocorticoids, and the general starting dose is l.2 mg kg-1 d-1 of prednisone (60-100 mg/d) or equivalent doses of other glucocorticoids. Symptoms often begin to improve after 1 to 2 months of use, and then the dose is gradually reduced. The reduction of hormone dosage should follow the principle of individualization. If the dose is reduced too quickly and the disease relapses, the dose must be increased again to control the disease. The dose must be increased again to control the disease. In patients with severe myopathy or with severe dysphagia, myocardial involvement or progressive interstitial lung disease, methylprednisolone shock therapy can be added by methylprednisolone 500-1000 mg daily by intravenous infusion for 3 days. Patients who do not respond to hormonal therapy should first consider whether the diagnosis is correct. If the diagnosis is correct, immunosuppressive therapy should be added; in addition, consideration should be given to whether the initial treatment time is too short or the drug is reduced too quickly; whether hormonal myopathy is present.
4.2 Immunosuppressive agents
4.2.1 Methotrexate (MTX): MTX is the most commonly used second-line agent for the treatment of PM/DM. MTX is not only helpful in controlling muscle inflammation, but also beneficial in improving skin symptoms and has a faster onset of action than azathioprine (AZA). The commonly used dose is 7.5 to 20 mg orally once a week.
4.2.2 AZA: The dose of AZA for PM/DM is 1~2 mg・kg-1・d-1 orally. AZA has a slow onset of action and should usually be administered for 6 months before judging whether it has a significant therapeutic effect on PM/DM.
4.2.3 Cyclosporine A (CsA): Currently, CsA is gradually being used for the treatment of PM/DM. It is mainly used for refractory cases where MTX or AZA treatment is ineffective. CsA has a faster onset of action than AZA, and the commonly used dose is 3-5 mg・kg-1・d-1. Blood pressure and renal function should be monitored during the use of CsA, and the drug should be stopped when the increase in serum creatinine is >30%.
4.2.4 Cyclophosphamide (CTX): CTX is not as commonly used as MTX and AZA in the treatment of myositis, and is not effective alone in controlling muscle inflammation, and is mainly used in cases with interstitial lung disease. It is mainly used in cases with interstitial lung lesions. It is administered as 2-2.5 mg・kg-1・d-1 orally, or 0.5-1.0 g/m2 intravenously monthly, the latter being more commonly used.
4.2.5 Antimalarial drugs: effective for skin lesions of DM, but no significant effect on muscle lesions. It should be noted that antimalarials can induce myopathy and patients develop progressive muscle weakness, which is easily confused with myositis progression. Muscle biopsy at this time can help in the identification of myopathy.
4.3 Intravenous immunoglobulin (IVIg)
For recurrent and refractory cases, IVIg can be considered. the routine therapeutic dose is 0.4g kg-1 d-1 for 5d per month for 3-6 months to maintain the efficacy. For DM-refractory rash, a small dose of IVIg (0.1 g kg-1 d-1 for 5 d per month for 3 months) can be added to achieve significant results. In general, IVIg has fewer adverse effects, but may manifest as headache, chills, chest discomfort, etc. IVIg should be contraindicated in patients with immunoglobulin deficiency.
4.4 Biological agents
In recent years there have been a number of studies with anti-tumor necrosis factor monoclonal antibodies, anti-B cell antibodies or anti-complement C5 for refractory PM or DM that may be effective. However, most of the studies are small samples or case reports. Definitive efficacy awaits burst of further studies with large samples.
4.5 Plasma exchange therapy
Some studies have shown that plasma exchange therapy has no significant effect on the treatment of PM/DM and may have only a “biochemical improvement”, i.e., a transient decrease in muscle enzymes without a significant effect on the overall course of the disease.
4.6 Combination of immunosuppressive agents
Combination therapy with 2 or more immunosuppressive agents is mainly used in relapsed or refractory PM/DM cases, but it has only been reported in case studies and there are no systematic clinical findings. The combination of MTX+CsA has been reported to be effective in treating hormone-resistant myopathy; CYC+CsA is effective in treating interstitial lung lesions in DM; and the combination of hormone+CsA+IVIg is more likely to maintain the remission status of myopathy than hormone+CsA treatment.