OBJECTIVES: To investigate the distribution of myositis-specific antibodies (MSA) in juvenile dermatomyositis (JDM) and the relationship between MSA and clinical features of JDM. METHODS: Clinical data of 72 children with JDM hospitalized from January 2020 to April 2025 were reviewed retrospectively, all of whom had been tested for MSA. The relationship between common MSA subtypes and clinical features was analyzed. RESULTS: Among the 72 children, 45 (62%) were positive for MSA, including 27 anti-NXP2-positive cases (38%), 10 anti-MDA5-positive cases (14%), and 3 anti-cN1A-positive cases (4%). Compared with the MSA-negative group, the anti-MDA5-positive patients showed significantly higher incidence rates of fever, arthritis, and interstitial lung disease (P<0.05). The anti-NXP2-positive patients exhibited significantly higher incidence rates of calcinosis, fever, soft tissue edema, and interstitial lung disease than the MSA-negative patients (P<0.05). Compared with the anti-MDA5-positive group and MSA-negative group, the anti-NXP2-positive group had significantly higher levels of creatine kinase and creatine kinase isoenzyme (P<0.017) and a significantly lower score of the Childhood Myositis Assessment Scale (P<0.017). CONCLUSIONS The positive rate of MSA is high in children with JDM, with different subtypes correlating with specific clinical manifestations and organ involvement. Detection of MSA is crucial for diagnosis and clinical management of JDM.
Humans ; Dermatomyositis/immunology* ; Male ; Female ; Child ; Retrospective Studies ; Interferon-Induced Helicase, IFIH1/immunology* ; Child, Preschool ; Autoantibodies/blood* ; Adolescent

INTRODUCTIONDermatomyositis (DM) is a multisystem inflammatory disease with a strong association with malignancy. We aimed to describe a series of Asian patients with DM and identify any significant clinical factors associated with malignancy.

MATERIALS AND METHODSThis was a retrospective review of a multi-racial cohort of 69 Asian patients diagnosed with DM over an 11-year period from 1996 to 2006.

RESULTSMalignancy was detected in 15 out of 68 patients (22%), the most common of which was nasopharyngeal carcinoma (7 cases). Compared to the non-malignancy group, the malignancy-associated group was older and had more male patients. There were no statistically significant clinical, serological or laboratory factors associated with a higher risk of malignancy.

CONCLUSIONThis study highlights the importance of ongoing malignancy screening especially for nasopharyngeal carcinoma in Asian patients with DM.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Carcinoma ; Confidence Intervals ; Dermatomyositis ; complications ; epidemiology ; immunology ; pathology ; Female ; Humans ; Logistic Models ; Male ; Middle Aged ; Muscle Weakness ; Nasopharyngeal Neoplasms ; epidemiology ; immunology ; pathology ; Odds Ratio ; Paraneoplastic Syndromes ; complications ; epidemiology ; immunology ; pathology ; Retrospective Studies ; Risk Factors ; Singapore ; epidemiology ; Young Adult

This study was performed in order to characterize the types of the infiltrating cells, and the expression profiles of major histocompatibility complex (MHC) class I and membrane attack complex (MAC) in patients with inflammatory myopathies and dysferlinopathy. Immunohistochemical stains were performed using monoclonal antibodies against several inflammatory cell types, MHC class I, and MAC in muscles from inflammatory myopathies and dysferlinopathy. There was significant difference in the types of infiltrating cells between polymyositis (PM), dermatomyositis (DM), and dysferlinopathy, including significantly high CD4+/CD8+ T cell ratio and B/T cell ratio in DM. In dysferlinopathy, CD4+ T cells were the most abundant and the proportions of infiltrating cell types were similar to those of DM. MHC class I was expressed in muscle fibers of PM and DM regardless of the presence of inflammatory infiltrates. MAC was expressed in necrotic fibers and vessels of PM and DM. One patient with early stage DM had a MAC deposits on endomysial capillaries. In dysferlinopathy, MAC deposit was also observed on the sarcolemma of nonnecrotic fibers. The analysis of inflammatory cells, MHC class I expressions and MAC deposits may help to differentiate dysferlinopathy from idiopathic inflammatory myopathy.
Adult ; Aged ; *Dermatomyositis/immunology/pathology ; Female ; Genes, MHC Class I ; Humans ; Male ; *Membrane Proteins/genetics/immunology ; Middle Aged ; Muscle Fibers, Skeletal/cytology/immunology/pathology ; *Muscle Proteins/genetics/immunology ; *Muscular Dystrophies, Limb-Girdle/immunology/pathology ; *Myositis/immunology/pathology ; *Polymyositis/immunology/pathology ; T-Lymphocytes/cytology/immunology/pathology ; Young Adult

A 13-year-old girl presented with multiple skin abscesses. She was diagnosed as having juvenile dermatomyositis (DM) at the age of 7 years. She had suffered from recurrent skin infections, atypical pruritic dermatitis and pneumonia since the age of 8 years. Bacteriologic and fungal cultures for skin abscesses and oral mucosa were positive S. aureus and C. albicans, respectively. Chemotactic defect in peripheral blood neutrophils was observed. The level of serum IgE was markedly elevated, and anti-S.aureus specific IgE was found. A diagnosis of hyperimmunoglobulin E-recurrent infection syndrome (HIE) was made and she was successfully treated with surgical drainage and antibiotics. To our knowledge, this is the first case report of HIE in a patient with juvenile dermatomyositis.
Adolescence ; Case Report ; Dermatomyositis/complications* ; Female ; Human ; IgE/blood ; Job's Syndrome/immunology ; Job's Syndrome/diagnosis ; Job's Syndrome/complications* ; Staphylococcal Infections/immunology ; Staphylococcal Infections/complications ; Staphylococcus aureus/immunology