Adult Onset Still’s Disease Presenting as Fever of Unknown Origin: A Case Report

26 years’ female patient attended triage with complaints of fever of almost 1-month duration. She was diagnosed as a case of Brucellosis outside. However, her fever persisted and she was finally diagnosed to have new onset adult-onset still’s disease (AOSD) with active macrophage activation syndrome (MAS) and multi organ failure. She met the diagnostic criteria for AOSD. She had high spiky fevers, hepatosplenomegaly, Lymphadenopathy, coagulopathy, anaemia with thrombocytopenia, hemophagocytosis, markedly elevated serum ferritin, low to absent natural killer (NK) cells, and remained unresponsive to steroids, intravenous immunoglobulin (IVIG) and hemophagocytic lymphohistiocytosis (HLH) protocol treatment. Interleukin-1 (IL1) inhibitors were not available. Interleukin-6 (IL6) blockers were not considered due to greater concerns about exacerbating bacterial infections with IL-6 blockade than with IL-1 blockade and much longer half-lives of the IL-6 inhibitors. We were also reluctant in using tocilizumab or sarilumab in new-onset disease where diagnostic uncertainty remains, as is often the case. She succumbed to her disease which had rapid fulminating course with multi organ failure. Her diagnostic and therapeutic challenges are discussed.