A case of adult-onset tubulointerstitial nephritis and uveitis ("TINU syndrome") associated with sacroileitis and Epstein-Barr virus infection with good spontaneous outcome

The authors report a case of tubulointerstitial nephritis and uveitis (TINU syndrome) in a 48-year-old woman. The patient's ocular symptoms (relapsing bilateral uveitis) began 4 months before the renal disease was diagnosed and were treated successfully with local steroid therapy. The main baseline laboratory findings were anemia, a rapid sedimentation rate, and a decreased renal function. Urinalysis results showed mild proteinuria and some hyaline and hyaline-granular casts. Immunoglobulin (Ig) G and IgM antibodies to Epstein-Barr virus (EBV) were present. The renal biopsy showed interstitial lymphocytes and infiltration by rare plasma cells, tubular atrophy without granulomas, and slight expansion of the mesangium; electronic microscopy showed rare electron-dense deposits in the mesangium; no vascular alterations were seen, and immunofluorescent staining was uniformly negative. X-ray of the pelvis showed bilateral sacroileitis, which has been previously described in only 1 case of TINU syndrome; human leukocyte antigen B27 was negative. After 6 months without any therapy, all laboratory findings were normal; after 30 months, renal function was still normal, uveitis had not relapsed, but sacroiliac involvement was still present; EBV-viral capsid antigen (VCA) IgM were still high (28 UA/mL), and the EBV IgG titers were increased (VCA>170, EBV-nuclear antigen 108 UA/mL). This case confirms that this rare entity, originally observed in children, may occur and have a favorable spontaneous renal outcome also in the adult; EBV may play a role, as previously suggested. This is, to the authors' knowledge, the first reported case of TINU syndrome with the association of a well-documented bilateral sacroileitis.