An unusual cause of fever of unknown origin

A 17 year old previously well black British born student was at college when he became feverish. He noticed a faint itchy rash over his arms and legs and was brought to the emergency department. He developed facial swelling and difficulty in swallowing and was admitted under the ear, nose, and throat team for suspected epiglottitis. On examination he had a faint maculopapular rash over his limbs, with submandibular lymphadenopathy and mild pharyngitis. Joint tenderness without effusions was elicited in both knees and elbows. No heart murmurs were heard. He had no family history of hereditary conditions and no history of allergy, foreign travel, or sexual relations. He had rising inflammatory markers, with a white cell count of 69×10⁹/L (4-11), neutrophils 65×10⁹/L (1.8-7.5), C reactive protein 163 mg/L (0-5), erythrocyte sedimentation rate 138 mm/h (3-15).

Liver function tests were deranged (alanine transaminase 577 U/L (10-40), alkaline phosphatase 117 U/L (40-129), bilirubin 50 µmol/L (1-17)). Ferritin was 50 000 µg/L (10-160). Blood cultures, malaria screen, antistreptolysin O antibody titre, hepatitis serology, cytomegalovirus, HIV, rheumatoid factor, antinuclear antibodies, and double stranded DNA were negative. Computed tomography of his neck, chest, and abdomen showed minimal reactive lymphadenopathy and 2 cm hepatomegaly. An echocardiogram was normal.

Despite four weeks of empirical antibiotic treatment he continued to have spiking fevers of more than 40°C. His rash faded away but the arthralgia was persistent.