A case of Crohn's disease complicated by adult onset Still's disease

Arthritis and arthralgia are the most common extra-intestinal manifestations of Inflammatory Bowel Disease (IBD), occurring in up to a third of patients. These may affect the peripheral or axial skeletal system and may or may not reflect disease activity. As a result, it is challenging to identify an alternative diagnosis to account for joint manifestations in the setting of IBD. We describe a case of a 30 year old woman with quiescent Crohn's colitis who presented with 2 weeks of fever, flitting arthralgia, a sore throat and a nocturnal rash on her thighs. She denied any gastrointestinal symptoms to suggest a flare up of IBD. Investigations revealed a neutrophilia and a markedly elevated serum ferritin. The patient met all four major and several minor Yamaguchi criteria for Adult Onset Still's Disease (AOSD). She was treated with corticosteroids and analgesia with resolution of her symptoms and normalisation of her biochemical markers. While joint manifestations are the most common extra-intestinal symptoms of Inflammatory Bowel Disease, atypical presentations should raise the concern of an additional diagnosis. This case represents a rare presentation of Crohn's disease complicated by AOSD.