An Unusual Case of Pyrexia of Unknown Origin.

A previously fit and well 29-year-old man with no significant recent travel or contact history presented to the hospital with 11 days of feeling unwell, intermittent diarrhea, abdominal pain and a skin rash that was consistent with folliculitis. Despite resolution of these index symptoms he continued with recurring fever of 38.5 degrees centigrade and weight loss of six Kilograms over the next three weeks. Extensive investigations to find a cause for the unexplained persistent fever failed to reveal an etiology, hence fulfilling pyrexia of unknown origin definition (PUO). None of the three main causes of PUO, namely infections, autoimmune diseases or underlying malignancy, were confidently found. Colonoscopy was suggested following a review of the abdominal CT scan to investigate possible thickening of the bowel wall. A diagnosis of atypically presenting Crohn's disease was eventually made and confirmed by colonoscopy and histology. The fever responded promptly to treatment of the Crohn's disease and he remained well at follow-up at six and 12 months after the initial presentation. In conclusion, it is important to keep in mind that PUO can be a rare initial presentation of inflammatory bowel disease in young adults with little or no gastrointestinal symptoms.