Refractory Relapsing-Remitting Adult-Onset Still's Disease in an Adolescent Female: A Rare Case Report.

Adult-onset Still's disease (AOSD) is a rare systemic autoinflammatory condition that presents with symptoms such as episodic fevers, a transient rash, inflammatory arthritis, and significant systemic inflammation. Diseases that have a relapsing-remitting clinical course can be challenging to diagnose and treat. We present a case of an 18 year old female with multiple flares over several years requiring stepwise escalation from conventional disease-modifying antirheumatic drugs (DMARDs) to targeted biologic therapy, highlighting the challenges of achieving durable remission. Our patient presented with recurrent episodes of high-grade fever (up to 40°C), evanescent salmon-pink rash, bilateral symmetrical inflammatory polyarthritis involving the wrists, metacarpophalangeal (MCP), proximal interphalangeal (PIP) joints, and knees with mild splenomegaly. After ruling out infectious, malignant, and other autoimmune diseases via biochemical, serological, autoimmune testing and biopsy, she was diagnosed with AOSD on the basis of the Yamaguchi criteria. Despite receiving treatment with corticosteroids and conventional disease-modifying antirheumatic drugs (DMARDs), including methotrexate, she suffered from multiple relapses, indicating a polycyclic disease pattern. The introduction of biologic therapy with tocilizumab provided temporary remission. However, her flares returned during the tapering of steroids, necessitating an increase in the dosage and the use of pulse corticosteroid therapy during the current admission. This case report illustrates the relapsing-remitting nature of AOSD. Escalation to IL-6 receptor inhibition (tocilizumab) is required in DMARDs refractory relapsing AOSD, with dose optimization to achieve sustained remission of disease activity of our patient.