RESUMEN
BACKGROUND: Juvenile dermatomyositis is a rare condition, but it is the most common idiopathic inflammatory myopathy in pediatric patients. AIM: To study the clinical manifestations, investigations, treatment, clinical course, and outcomes of juvenile dermatomyositis in Thai children. METHOD: This retrospective study included juvenile dermatomyositis patients treated at Siriraj Hospital, a 2,300-bed national tertiary referral center in Bangkok, Thailand, from 1994 to 2019. RESULTS: Thirty patients (22 females and 8 males) were included with a female to male ratio of 2.7:1. Median age at diagnosis was 5.1 years (range, 2.6-14.8 years). Median duration of illness before diagnosis was 6.5 months (range, 0.3-84.0 months). Acute and subacute onset occurred in the majority of patients. Presenting symptoms included muscle weakness in 27/30 (90%), skin rash in 26/30 (86.7%), muscle pain in 17/26 (65.4%), and arthralgia in 4/18 (22.2%) of patients. Dermatologic examination revealed Gottron's rash, heliotrope rash, and periungual telangiectasia in 25/30 (83.3%), 21/30 (70.0%), and 15/24 (62.5%) of patients, respectively. Interestingly, scalp dermatitis was found in 8/21 (38.1%) of patients. The most commonly used treatment regimen in this series was a combination of prednisolone and methotrexate. During the median follow-up of 3.1 years (range, 0.0-18.5 years), only one-third of patients were seen to have monocyclic disease. Extraskeletal osteosarcoma at a previous lesion of calcinosis cutis was observed in one patient at 12 years after juvenile dermatomyositis onset. LIMITATIONS: This was a retrospective single-center study, and our results may not be generalizable to other healthcare settings. Prospective multicenter studies are needed to confirm the findings of this study. CONCLUSION: juvenile dermatomyositis usually poses a diagnostic and therapeutic challenge, which can be compounded by the ethnic variations in the clinical presentation, as observed in this study. Asian patients tend to present with acute or subacute onset of disease, and arthralgia and/or arthritis are less common than in Caucasian patients. Scalp dermatitis is not uncommon in pediatric juvenile dermatomyositis patients. An association between juvenile dermatomyositis and malignancy, though rare, can occur.