Dupilumab-Induced Myalgia and Enthesitis in a Pediatric Patient Treated for Severe Atopic Dermatitis.

Dupilumab is a monoclonal antibody systemic therapy approved for the treatment of atopic dermatitis (AD). It works by blocking the signaling pathways of interleukin-4 (IL-4) and interleukin-13 (IL-13). This case report describes a 10-year-old male with severe AD who developed myalgia and enthesitis suspected to be induced by dupilumab. The patient developed severe myalgia after a month of being on dupilumab, although his eczematous skin rash showed considerable improvement after treatment initiation. His pain was restricting movement and leading to contractures, which made him unable to walk or stand independently. A thorough diagnostic workup, which included rheumatological, brain, and spine imaging studies, was done to exclude other possible causes. Treatment with dupilumab was stopped, and the patient was advised to undergo physiotherapy and serial casting to restore his muscle function and for the correction of contractures. While dupilumab is regarded as a safe and well-tolerated medication, this report illustrates uncommon adverse effects of the drug that are rarely described in the pediatric population and may contribute to considerable morbidity. A probable underlying mechanism may involve an interaction between the IL-4/IL-13 axis and the IL-17/IL-23 axis, which also play a role in autoimmune arthritis. The report focuses on the significance of close monitoring for musculoskeletal symptoms in patients receiving dupilumab and emphasizes the need for prompt drug discontinuation if such manifestations occur.