1. Clinical Significance of Myositis Antibodies:
Helps in IIM classification; predicts IIM progression; aids in predicting complications of IIM; assists in determining treatment plans for IIM. Myositis antibody spectrum 10-year survival rate observation: anti-SRP > anti-HMGCR > anti-Mi-2 > anti-NXP-2 > anti-SAE > anti-TIF1-Υ > anti-MDA5.
2. NXP-2 Antibody:
① Most common antibody in JDM;
② Associated with subcutaneous calcification in young people, divided into with and without calcification deposition. Clinical characteristics with calcification deposition: younger onset age, severe rash, mild muscle weakness, no tumors, NXP-2 levels unrelated to disease activity, difficult to treat calcification deposition. Clinical characteristics without calcification deposition: severe muscle weakness, difficulty swallowing, peripheral limb edema.
③ Associated with tumors in the elderly.
3. SAE Antibody
Clinical Characteristics:No difference between Eastern and Western populations
① Unique skin lesions, pigmentation-like rashes;
② More frequent swallowing difficulties;
③ Mild muscle weakness;
④ No difference in response to hormone + immunosuppressive therapy.
4. TIF1-Υ Antibody Clinical Characteristics:
Persistent facial rash resembling drunkenness; rash along the hairline; highly associated with tumors; positive for this antibody is a risk marker for tumor occurrence; severe muscle weakness, severe swallowing difficulties.
5. Mi-2 Antibody:
Low positivity rate, easily combined with other myositis antibodies, clinical manifestations typical of dermatomyositis, muscle weakness, significantly elevated CK, 1/3 develop ILD, 1/4 have esophageal involvement and tumors, responsive to immunosuppressive therapy.
6. Anti-Synthetase Antibodies:
70% positivity in females, average onset age around 50, clinical symptoms similar, good response to hormone + immunosuppressive therapy but prone to relapse, overall prognosis good. However, patients positive for anti-PL7/PL12 are more likely to have early severe ILD and gastrointestinal complications, especially intestinal obstruction.
7. Anti-MDA5 (+) Antibody
Clinical Significance:60% are non-myopathic dermatomyositis, skin ulcerative rashes, hair loss; associated with A/SIP (RP-ILD), poor prognosis.
8. IMNM Spectrum:
Subacute proximal muscle weakness, lower limb weakness > upper limb weakness, persistent CK significantly elevated (thousands to tens of thousands), may be associated with visceral involvement such as ILD, but generally mild, may be associated with tumors; conventional hormone and immunosuppressive therapy ineffective, prone to relapse.
9. Serum Markers Anti-HMGCR and SRP Antibodies:
Clinical Features of Anti-SRP Positive IMNM:PM positivity rate 21.43%, DM 0%, higher incidence of swallowing difficulties in antibody-positive individuals, low incidence of severe cardiac complications, no significant association with pulmonary interstitial disease, pathology shows necrotizing myositis, treatment responses vary.
Clinical Features of Anti-HMGCR Positive IMNM:Both PM/DM patients can have HMGCR antibodies, positivity rate 5%, HMGCR antibody positivity associated with pathological features of necrotizing myositis; no obvious correlation with statin use.
Speaker: Professor Wang Guochun, China-Japan Friendship Hospital
Organizer: Wang Xiujuan, Hohhot City People’s Hospital
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