By: Mirelle Alktaish, Jesse Lamb, Jamesetta Polahn, ,Ilana Nathan, Hawraa Beydoun, Arielle Preston

This case discusses the findings of a 5-month-old Hispanic male, who initially presented with 5 days of fever, 3 days of diarrhea and rash, and 2 days of vomiting. He had been diagnosed with acute otitis media by his primary care physician 3 days prior to his presentation and started on amoxicillin. He was brought to the ED because of his persistent fever up to 104°F and decreased oral intake. At the time of presentation, there were multiple entities in the differential diagnosis including meningitis, acute gastroenteritis, a urinary tract infection, anemia and/or a viral infection. Despite the broad differential diagnosis, no one diagnosis could account for the variety of findings, making it more difficult to develop a definitive treatment plan. The patient’s ongoing condition of high fever continued to progress for more than 7 days with the physicians eventually classifying it into the broad category of Fever of Unknown Origin (FUO). The patient was treated with antibiotics for suspected bacterial meningitis versus pyelonephritis, without improvement. Eventually the results of an echocardiogram and further testing confirmed the diagnosis of Incomplete Kawasaki Disease (IKD). In patients under 6 months, IKD can be considered with a fever ≥7 days with no other clinical findings.  In patients over 6 months, IKD can be considered with ≥5 days of fever and ≤ 4 of the 5 criteria fulfilled.  The unknown etiology of Kawasaki Disease and its complications of inflammation, aneurysm, and necrosis of the coronary artery makes it the most common cause of acquired heart disease in children and an important differential in a case of FUO. This case highlights the importance of atypical presentations in any disease process, and the necessity of keeping a broad differential diagnosis that gets revised with time and further testing, especially in a patient with diverse clinical findings.