Urticarial rash, fever, and arthritis: A case of refractory Adult‐onset Still's disease with good response to tocilizumab

Adult‐onset Still's disease (AOSD) is a rare, systemic inflammatory disorder of not completely understood etiology. Aberrant activation of the innate immune system and overproduction of several pro‐inflammatory mediators are considered a critical component in disease pathogenesis. AOSD still poses a challenge due to the broad range of differential diagnoses and no specific biomarkers. Four cardinal symptoms are quotidian spiking fever, joint involvement, evanescent salmon pink‐rash rash, and leukocytosis with neutrophilia. We present a case of a 61‐year‐old female with a recurrent urticarial rash accompanied by attacks of high fever, tender joints, sore throat, enlarged liver, elevated inflammatory reactants, and hyperferritinemia. After an extensive workup, the patient fulfilled the criteria of AOSD. She was refractory to the glucocorticosteroids and disease‐modifying anti‐rheumatic drugs (DMARDs). Finally, after several unsuccessful attempts to achieve disease control with traditional DMAR's administration of Tocilizumab (TCZ), a humanized anti‐IL‐6 receptor antagonist resulted in substantial disease improvement. Since skin manifestations are a common feature of AOSD, it should be among differential diagnoses in patients with skin lesions and constitutional symptoms. Biologic agents represent a significant therapeutic advance in patients with AOSD refractory to conventional therapy.