Sore Throat to Still's: Group A Streptococcus Causing Adult-Onset Still's Disease

Adult-onset Still's disease (AOSD) is a rare hyper-inflammatory disease with poorly understood etiology, often presenting with nonspecific symptoms such as fever, inflammatory polyarthralgia, transient salmon-pink maculopapular rash, lymphadenopathy, and hepatosplenomegaly. We are presenting an unusual case of AOSD triggered by Group A streptococci (GAS) throat infection. We report the case of a 37-year-old male with no significant medical history admitted to medicine service after three emergency room (ER) visits. Our patient had a confirmed GAS throat infection and initially met the Jones criteria. However, further testing revealed significantly high inflammatory markers, clinically evident symmetrical synovitis in wrists and left knee, and widespread lymphadenopathy with worsening maculopapular rash. Given this, he met the Yamaguchi criteria, resulting in a diagnosis of AOSD. Group A Streptococcus infections are usually linked to acute rheumatic fever (ARF), but in our case, we believe GAS infection triggered the cascade of inflammatory responses resulting in AOSD. The patient received treatment with non-steroidal anti-inflammatory drugs (NSAIDs) and high-dose steroids with a resolution of arthralgia, down-trending ferritin, and clinical improvement in a skin rash. To the best of our knowledge, we are reporting the first case of GAS-triggered AOSD, highlighting the need to uncover atypical causes for AOSD and warranting the need to investigate triggers for AOSD.