Usefulness of renal diffusion-weighted magnetic resonance imaging for early diagnosis of tubulointerstitial nephritis and uveitis (TINU) syndrome.

A teenage girl presented with fever after aspirin use. Examination revealed no organ-specific symptoms. The serum creatinine level and urine analysis findings were normal. The drug lymphocyte stimulation test was positive for aspirin. Diffusion-weighted magnetic resonance imaging (DW-MRI) revealed hyperintensity in both kidneys although serum creatinine was only mildly elevated. A subsequent kidney biopsy confirmed acute interstitial nephritis (AIN). She later developed uveitis and the final diagnosis was tubulointerstitial nephritis and uveitis (TINU) syndrome, possibly triggered by aspirin, requiring systemic and topical corticosteroid therapies. TINU syndrome should be considered in young patients with fever of unknown origin and a history of nonsteroidal anti-inflammatory drug use. This is the first reported case suggesting the usefulness of DW-MRI, which is safe for children without exposure to ionising radiation, in detecting early-stage AIN before apparent kidney impairment.