An unexpected duo; case report of tubulointerstitial nephritis and uveitis syndrome in systemic sclerosis

Tubulointerstitial nephritis and uveitis (TINU) syndrome is a rare immune-mediated disorder usually affecting young individuals. Corticosteroids are considered the mainstay of therapy, although alternative immunosuppressive strategies may be required when contraindications exist. We report a 71-year-old woman with no prior kidney disease who presented with bilateral anterior uveitis and acute renal failure. Laboratory tests showed hematoproteinuria and positive antinuclear and anti-centromere antibodies. Renal biopsy revealed acute interstitial nephritis with inflammatory infiltrates and nephroangiosclerosis. Clinical and serological findings met EULAR criteria for systemic sclerosis. To avoid the risk of scleroderma renal crisis associated with corticosteroid therapy, mycophenolate mofetil (MMF) was initiated as monotherapy. Progressive renal recovery was observed, with serum creatinine (sCr) decreasing from 4.4 mg/dL to 1.3 mg/dL after six months, and stabilization at 1.1 mg/dL following MMF withdrawal. This case explains the diagnostic challenges of TINU in an elderly patient with systemic sclerosis and reports, to our knowledge, the first successful use of MMF monotherapy. MMF may represent a valuable alternative in corticosteroid-contraindicated cases, warranting further evaluation in future studies.