Adult-Onset Still's Disease Presenting with Progressive Motor Neuropathy

Adult-onset Still's disease (AOSD) is a rare systemic autoinflammatory disorder characterized by dysregulation of the innate immune system and excessive cytokine production. Its presentation is often non-specific and heterogeneous, making diagnosis challenging and one of exclusion.

We report the case of an 18-year-old woman admitted with quotidian fever, frequent episodes of tonsillitis, intermittent skin rash and progressive distal lower limb weakness. Neurological assessment demonstrated progressive motor neuropathy. Laboratory findings revealed neutrophilic leucocytosis, significantly elevated inflammatory markers and hyperferritinaemia. Extensive investigation excluded infectious, malignant and autoimmune causes, and the patient met the Yamaguchi classification criteria for AOSD. Treatment with systemic corticosteroids, colchicine and the interleukin-1 receptor antagonist resulted in rapid and sustained clinical improvement.

This case highlights the diagnostic complexity of AOSD and emphasizes the importance of considering this diagnosis in patients with persistent fever, hyperferritinaemia and rare neurological manifestations.

Adult-onset Still's disease should be considered in patients with fever of unknow origin and hyperferritinaemia.Neurological involvement, including polyneuropathy, may occur as an atypical manifestation.Early cytokine-targeted therapy is associated with rapid clinical improvement and better outcomes.