Tu105 - Adult-onset Still’s Disease in a Young Adult Patient Presenting as Fever of Unknown Origin Treated with Tocilizumab: A Case Report

Katrina Joy Chua, Doctor – Consultant, Rheumatology, St. Luke's Medical Center - Quezon City; Elaine Tan, Doctor – Fellow, Rheumatology, St. Luke's Medical Center - Quezon City

Abstract Text: Adult-onset Still’s disease (AOSD) is a rare systemic inflammatory disorder characterized by quotidian pattern of fever in the absence of infections, malignancies, and rheumatic diseases. Other features include evanescent rash, arthralgia, sore throat, lymphadenopathy, splenomegaly, leukocytosis, liver dysfunction, and negative anti-nuclear antibody (ANA) and rheumatoid factor (RF). AOSD has been associated with markedly elevated serum ferritin concentrations.

We report a case of a 29-year-old female presenting with fever with maximum temperature of 40C for 1 month duration, evanescent rash, sore throat, myalgia, arthralgia, and rash. Laboratory examination showed leukocytosis (WBC 18,400), transaminitis (ALT 175, AST 281), and hyperferritinemia (63,281ng/mL). Extensive work-up to look for infectious and malignant causes were unremarkable. ANA and RF were both negative. She was able to fulfill the Yamaguchi classification criteria for the diagnosis of AOSD. Glucocorticoid therapy was started, however, she remained to be symptomatic. Increased levels of interleukin-6 (IL-6) and other pro-inflammatory cytokines have been shown in AOSD. Tocilizumab is an IL-6 receptor antagonist monoclonal antibody that can be used as an alternative to anakinra. The patient received tocilizumab at a dose of 8 mg/kg with immediate relief of symptoms. Serum ferritin and transaminase levels decreased to 5105ng/mL and 126 U/L, 85 U/L, respectively.

In this case report, tocilizumab is an effective and well-tolerated treatment option for patients with AOSD with predominantly systemic symptoms.