Characteristics of coexisting localized scleroderma and inflammatory arthritis

Localized scleroderma (LS), including morphea and linear scleroderma, is an autoimmune disease where excessive subcutaneous collagen deposits lead to thickening, scarring, and fibrosis of the tissues. LS coexisting with inflammatory arthritis is less well-described but has been reported in as many as 20% of 53 LS patients in a recent cohort. Herein, we describe a cohort of 8 children with both LS and inflammatory arthritis. The objective of this study is to determine the characteristics of inflammatory arthritis in children with LS and their response to treatment regimens.

A retrospective chart review was completed on patients less than 19 years of age who were diagnosed with either morphea or linear scleroderma at the Children of Alabama center from 2004-2018. Patients were identified using ICD-9 and ICD-10 diagnostic codes. Records were reviewed for additional diagnostic codes, exams, and laboratory findings confirming coexisting inflammatory arthritis and LS.

A total of 87 patients with a diagnosis of either morphea or linear scleroderma were identified. Eight (9%) had coexisting inflammatory arthritis according to the diagnostic codes with documented active arthritis. Median age of initial rheumatic disease diagnosis was 7.5 years. A majority of patients with both LS and inflammatory arthritis were female (62.5%). Half of the patients (n=4, 50%) had LS lesions over arthritic joints. All of the identified patients were diagnosed with a form of juvenile idiopathic arthritis (JIA). The JIA diagnoses varied widely in 3 (37.5%) patients with rheumatoid factor (RF) negative polyarticular JIA, 2 (25%) with oligoarticular JIA, 2 (25%) with psoriatic JIA, and 1 (12.5%) with enthesitis-related JIA. The timing of onset of LS and inflammatory arthritis varied widely. Three (37.5%) patients had LS lesions preceding clinical arthritis, and three (37.5%) had arthritis before the appearance of LS. Two (25%) patients had both LS and arthritis at the time of diagnosis. All patients received methotrexate (MTX) during their disease course with only 3 (37.5%) receiving systemic steroids during treatment. All 8 patients showed resolution of LS lesions. However, 6 of the 8 patients demonstrated active arthritis on combination MTX and TNFi therapy.

In this cohort of pediatric LS, 9% of patients had coexisting inflammatory arthritis. The characteristics of this cohort varied widely. All patients received MTX initially and showed a resolution of LS lesions. However, in the majority of patients, the arthritis failed to respond to MTX and TNFi combination therapy. These results suggest that inflammatory arthritis coexisting with LS may be less likely to respond to traditional inflammatory arthritis or JIA therapies.