Objective: To obtain data concerning a history of infection occurring in the 3 months before recognition of the typical weakness and rash associated with juvenile dermatomyositis (JDM).Methods: Parents or caretakers of children within 6 months of JDM diagnosis were interviewed by the registry study nurse concerning their child's symptoms, environment, family background, and illness history. Physician medical records were reviewed, confirming the JDM diagnosis.Results: Children for which both a parent interview and physician medical records at diagnosis were available (n = 286) were included. Diagnoses were as follows: definite/probable JDM (n = 234, 82%), possible JDM (n = 43, 15%), or rash only (n = 9, 3%). The group was predominantly white (71%) and had a girl:boy ratio of 2:1. Although the mean age at onset was 6.7 years for girls and 7.3 years for boys, 25% of the children were ≤4 years old at disease onset. In the 3 months before onset, 57% of the children had respiratory complaints, 30% had gastrointestinal symptoms, and 63% of children with these symptoms of infection were given antibiotics.Conclusion: This study provides evidence that JDM affects young children. The symptoms of the typical rash and weakness often follow a history of respiratory or gastrointestinal complaints. These data suggest that the response to an infectious process may be implicated in JDM disease pathogenesis.

Objective: To determine the association of changes on nailfold capillaroscopy with clinical findings and genotype in children with juvenile dermatomyositis (DM), in order to identify potential differences in disease course over 36 months.Methods: At diagnosis of juvenile DM in 61 children prior to the initiation of treatment, tumor necrosis factor α (TNFα) −308 allele and DQA1*0501 status was determined, juvenile DM Disease Activity Scores (DAS) were obtained, and nailfold capillaroscopy was performed. The disease course was monitored for 36 months. Variations within and between patients were assessed by regression analysis.Results: At diagnosis, shorter duration of untreated disease (P = 0.05) and a lower juvenile DM skin DAS (P = 0.035) were associated with a unicyclic disease course. Over 36 months, end‐row loop (ERL) regeneration was associated with lower skin DAS (P < 0.001) but not muscle DAS (P = 0.98); ERL regeneration and decreased bushy loops were associated with a shorter duration of untreated disease (P = 0.04 for both). At 36 months, increased ERL regeneration (P = 0.007) and improvement of skin DAS (P < 0.001) and muscle DAS (P = 0.025) were associated with a unicyclic disease course.Conclusion: Early treatment of juvenile DM may lead to a unicyclic disease course. The non‐unicyclic disease course usually involves continuing skin manifestations with persistent nailfold capillaroscopy changes. The correlation of nailfold capillaroscopy results with cutaneous but not with musculoskeletal signs of juvenile DM over a 36‐month period suggests that the cutaneous and muscle vasculopathies have different pathophysiologic mechanisms. These findings indicate that efforts to identify the optimal treatment of cutaneous features in juvenile DM require greater attention.

Objective: To determine if mycophenolate mofetil (MMF) diminishes skin and muscle disease activity in children with juvenile dermatomyositis (DM), thereby permitting a decrease in corticosteroid dose.Methods: A retrospective data review for 50 children with juvenile DM (mean ± SD age 12.2 ± 5.0 years) who had received MMF for 12 months identified the following characteristics: 38 (76%) were girls, 39 (78%) were white, 10 (20%) were Hispanic, and 1 (2%) was African American. The MMF dose and frequency, type of infection, white blood cell (WBC) count, corticosteroid dose, and the validated disease activity score (DAS) subscores for skin (DAS‐S) and muscle (DAS‐M) were obtained.Results: Twelve months after the start of MMF, the mean ± SD DAS‐S decreased from 5.24 ± 0.29 to 3.72 ± 0.29 (P = 0.001), and the mean ± SD DAS‐M decreased from 2.44 ± 0.39 to 1.17 ± 0.28 (P = 0.002). The mean ± SD prednisone dosage decreased from 0.39 ± 0.06 to 0.23 ± 0.02 mg/kg/day (P = 0.0001), with resumption of linear growth (P = 0.008). The WBC/lymphocyte count was unchanged over the 12 months on MMF. The infection rate was assessed in a subset of 26 children with juvenile DM who were observed for 12 months before the start of MMF and then compared with the ensuing 12 months of MMF therapy. There was no significant difference between the pretreatment period and the first 6 months of MMF therapy (P = 0.44), but the infection rate decreased in months 7–12 (P = 0.001).Conclusion: MMF appears to be worthy of consideration as an additional therapeutic modality for treatment of children with juvenile DM. These data suggest that the use of MMF decreases skin and muscle disease activity and is steroid sparing. MMF appears to be well tolerated, but patients should be monitored for infection.

Despite the increased use of rituximab in treating pediatric patients with autoimmune diseases in the last decade, there are limited data on rituximab safety in those subjects who have a developing immune system. The objective of this study is to determine the prevalence of hypogammaglobulinemia in children with autoimmune disease receiving rituximab within the first three years of treatment in the pediatric rheumatology clinic at a tertiary care center. We conducted a retrospective chart review of 63 pediatric subjects who received rituximab for the treatment of their autoimmune disease. Immunoglobulin gamma (IgG) levels, immunosuppressive medication and the need for immunoglobulin replacement therapy were evaluated. Hypogammaglobulinemia was defined as a serum IgG level less than two standard deviations below the mean for age-matched healthy controls. Twenty-eight patients (44%) were found to have hypogammaglobulinemia. Hypogammaglobulinemia occurred within the first six months of rituximab treatment in the majority of patients (22 out of 28). The occurrence of hypogammaglobulinemia varied based on the rituximab indication: 46% pediatric Systemic Lupus Erythematosus (SLE), 71% autoimmune CNS disease, 60% ANCA vasculitis, and 12% in the miscellaneous group. Autoimmune CNS disease had more severe hypogammaglobulinemia, more persistent and was associated with more frequent or severe infections. Three patients with autoimmune CNS disease and one with SLE were given IgG replacement therapy to prevent recurrent or severe infections. The prevalence of hypogammaglobulinemia in rituximab treated children with autoimmune disease seems to be higher than published data for adults, especially for children with autoimmune CNS disease. The onset of hypogammaglobulinemia is usually within six months of initiation of rituximab therapy. We recommend: 1) obtaining an IgG level prior to starting rituximab; 2) close monitoring for hypogammaglobulinemia after the use of rituximab in pediatric patients and 3) early institution of immunoglobulin replacement therapy if patients develop recurrent infections.