2026-07-10 | Vedolizumab as a rescue therapy for severe gastrointestinal involvement in anti-NXP2 positive juvenile dermatomyositis
Şengül Çağlayan, Ulaş Emre Akbulut, Tangül Pınarcı, Muhammed Gültekin Kutluk, Hasan Serdar Kıhtır; Vedolizumab as a rescue therapy for severe gastrointesti
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2026-07-07 | Anti-Melanoma Differentiation-Associated Gene 5 Antibody-Positive Juvenile Dermatomyositis Presenting With Predominant Joint Contractures.
Anti-melanoma differentiation-associated gene 5 (MDA5) positive juvenile dermatomyositis (JDM) (anti-MDA5+ JDM) is a distinct subtype of JDM characterized by marked clinical heterogeneity. Although cutaneous manifestations and interstitial lung disease (ILD) are well recognized, atypical musculoskeletal presentations may lead to diagnostic delay. We report a 16-year-old male with anti-MDA5+ JDM who presented with progressive joint contractures as the predominant manifestation over a 2-year period. The patient also exhibited restricted mouth opening, with a classical dermatomyositis (DM) cutaneous rash absent or only mild, and proximal muscle weakness, mild to moderate. Laboratory evaluation revealed high-titer anti-MDA5 antibodies and a markedly elevated serum immunoglobulin E (IgE) level. Magnetic resonance imaging (MRI) demonstrated periarticular and soft-tissue involvement, and muscle biopsy confirmed pathological features consistent with DM. Treatment with systemic glucocorticoids in combination with methotrexate resulted in substantial improvement in joint mobility, with good tolerability during follow-up. Progressive contractures can occasionally become the predominant presenting manifestation in anti-MDA5+ JDM and contribute to diagnostic delay. This case underscores the importance of early evaluation for idiopathic inflammatory myopathies (IIM), including myositis-specific antibody (MSA) testing and muscle biopsy, in adolescents with unexplained progressive joint contractures.
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2026-06-16 | Population Pharmacokinetics and Initial Dosage Recommendation of Tacrolimus in Children with Juvenile Dermatomyositis.
There is a gap in the pharmacokinetic data on tacrolimus in children with juvenile dermatomyositis (JDM). This study aimed to develop a population pharmacokinetics (PopPK) model for tacrolimus in patients with JDM and formulate model-based recommended dosing regimens. The PopPK model for tacrolimus was retrospectively developed in 31 children with JDM using nonlinear mixed-effects modeling. The trough concentrations of tacrolimus at different doses were simulated using the Monte Carlo method in children with different body weights. The one-compartment model with first-order absorption and elimination best described the pharmacokinetic data of tacrolimus. In the final model, body weight and concomitant use of voriconazole (VRC) significantly affected the apparent clearance (CL/F) of tacrolimus. The calculation of interindividual clearance was performed as follows: 12.635 × (WT/33.5)0.296 × (1-0.426 × VRC). The tacrolimus CL/F ratio in children with JDM was 1:0.574 between those without VRC coadministration and those with VRC coadministration at equivalent body weights. For patients with JDM and body weights of 10-20, 20-30, 30-40, and 40-60 kg, the recommended initial doses of tacrolimus without the combined use of VRC were 0.12, 0.08, 0.06, and 0.05 mg·kg-1·d-1 (q12h), respectively; the recommended initial doses of tacrolimus with the combined use of VRC were 0.07, 0.05, 0.04, and 0.03 mg·kg-1·d-1 (q12h), respectively. This is the first study to establish a PopPK model for tacrolimus. Drug dosage regimens devised on the basis of this model provide evidence-based recommendations for patients with JDM.
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