Background/Purpose: Persistent skin manifestations, in particular calcinosis, contribute to significant morbidity in patients with JDM. The goal of this study was to compare the course of skin vs muscle symptoms and document the frequency of calcinosis in children with JDM.

Methods: Data were extracted from the Lurie Children’s CureJM Center of Excellence’s Juvenile Myositis Registry, a dataset that includes all children diagnosed with definite/probable JDM based on Bohan and Peter criteria (n=485). The duration of untreated disease (DUD), the interval between first symptom and start of therapy was calculated.  The children were assessed for calcifications and for extent of disease, using the JDM Disease Activity Score (DAS) for skin (DAS-S), muscle (DAS-M) and total (DAS-T). Among this dataset were data on 184 untreated children with JDM, seen from July, 1971 to May, 2019. A paired t-test was used to analyze differences in mean DAS scores at baseline and 6, 12, 24, and 36 months on medication; as well as time to reach clinically inactive skin vs. muscle scores (DAS 0, ≤1, ≤2). Differences in time for abnormal vascular elements in DAS-S to resolve was calculated using a one-way ANOVA.

Results: 138 girls (75%) and 46 boys (25%) with untreated JDM and a mean age of 7.1±3.9 (mean±SD) years were enrolled and followed for 6.6±5.5 years. At baseline, the mean DAS-Muscle (DAS-M) score was 4.9±1.4 compared to DAS-Skin (DAS-S) score of 5.8±3.0 (p< 0.01). DAS-S was persistently higher than DAS-M at 6, 12, 24, and 36 months of treatment and reached 0/clear, ≤1/almost clear, and ≤2/mild later than DAS-M. The mean time to reach a DAS score of 0 was 18.4±20.4 months for skin compared to muscle of 9.5±9.9 months (p< 0.001). Altogether, 92% reached clinical inactivity for skin compared to 97% for muscle (p< 0.05). Of the vascular features in DAS-S, eyelid margin capillary dilatation was seen most frequently (54%) and persisted longest before clearance at a mean duration of 7.8±14.5 months. This was significantly longer than recovery time for periungual capillary telangiectasia (3.5±4.0 months) (p< 0.05) and palate vessel dilatation (3.3±3.2 months) (p< 0.05). 9 (5%) patients had calcifications at baseline and an additional 23 (15%) developed calcifications during the course of disease. The majority (83%) of calcifications were classified as mild. Calcifications developed after a mean of 64.7±71.5 months on medication and took an average of 6.1±7.0 months to resolve. 26% (6 out of 23) of patients had a recurrence of calcification at the same site; calcifications never resolved in 7 patients, 5 of whom (71%) had calcifications at first visit. These 7 children had a mean duration of untreated disease (DUD) at diagnosis of 60.2±44.5 months, in comparison to the children whose calcifications resolved, who had a mean DUD at diagnosis of 12.5±14.8 (p< 0.001).

Conclusion: Skin disease presents with greater activity and persists longer than muscle disease in children with JDM. Vascular features within skin, particularly eyelid margin capillary dilatation, tend to be most persistent. Early and aggressive treatment can limit the severity and persistence of calcifications that recur late in the disease course.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/skin-disease-more-recalcitrant-to-intervention-than-muscle-disease-a-long-term-prospective-study-of-184-children-with-juvenile-dermatomyositis/