A previously healthy, immunized, 15-month-old girl was admitted with 2 weeks of daily intermittent fevers and 3 days of decreased intake, irritability, and an intermittent cough. Systems review was otherwise unremarkable, including no history of torticollis, neck swelling, neck pain, or drooling. She was not on any home medications except acetaminophen as needed. There was a sick contact at daycare with Streptococcal tonsillopharyngitis, and her mother had a mild cough and congestion. There was no travel history.
Examination demonstrated fever (up to 40.5 C) with otherwise normal vital signs and no distress. She had small, nontender bilateral cervical lymphadenopathy, a clear oropharynx, no conjunctivitis, and no oral or extremity changes. Cardiovascular, respiratory, abdominal, and joint examinations were normal. A faint erythematous maculopapular rash was noted on her legs.
A multidisciplinary approach to fever of unknown origin (FUO) in a toddler was taken, which included Infectious Disease, Oncology, and Rheumatology specialist consultation. An extensive infectious workup was negative. This included blood, urine, and throat cultures, as well as testing for tuberculosis, Epstein-Barr virus, human immunodeficiency virus, parvovirus, adenovirus, cytomegalovirus, and hepatitis A, B, and C. Chest radiograph, abdominal ultrasound, and blood smear demonstrated no evidence of any malignant processes. Further investigations revealed elevated inflammatory markers, including a white blood cell count (16 x 109/L; reference range = 6.5-13 x 109/L), C-reactive protein (290 mg/L; 0.1-1 mg/L), erythrocyte sedimentation rate (76 mm/h; 2-34 mm/h), and ferritin (523 microg/L; 5-100 microg/L), with an associated normocytic anemia (hemoglobin 87 g/L; 102-127 g/L). Liver enzymes, platelets, albumin, and an echocardiogram were unremarkable.
With no identifiable infectious or oncologic etiology, the patient was managed with supportive care. Despite no direct evidence apart from prolonged fever and elevated inflammatory markers (including anemia, an indirect sign of inflammation), she was treated with intravenous immunoglobulin on day 18 of fever for concern of atypical Kawasaki disease. Although this resulted in some clinical improvement, her fevers persisted. Subsequently, indomethacin was trialed for suspicion of an undeclared systemic juvenile idiopathic arthritis. Given that her oral intake and fevers were improving, and no new symptoms had developed, she was discharged home on day 20 of fever with close follow-up arranged.
The patient re-presented to the emergency department 4 days later with persistent fevers, intermittent stridor, drooling, and coughing when drinking. Further imaging revealed the diagnosis.