Granulomatous tubulointerstitial nephritis in a renal allograft: three cases report and review of literature.

Granulomatous interstitial nephritis (GIN) is a rare histologic diagnosis in renal allografts. We report three cases with GIN. Case 1: a 37-yr-old woman received a kidney from her mother. On follow-up 15 months later, serum creatinine was increased and a graft biopsy showed epithelioid granuloma in the center of massive mononuclear cell infiltration. She had presented with refractory urinary tract infection treated with antibiotics before biopsy. The case was presumed to be GIN associated with UTI or hypersensitivity to medication. Case 2: a 47-yr-old woman received a second graft from a non-heart-beating donor. A protocol graft biopsy was performed six months after transplantation and showed several granulomatous nodules. She was followed closely without therapy. Case 3: a 27-yr-old woman received an ABO-incompatible kidney from her father. A protocol graft biopsy was performed three months after transplantation and showed granulomatous reaction with severe mononuclear cell infiltration. She received steroid pulse therapy. The two latter patients had no obvious factor contributing to GIN. Therefore, they were presumed to have idiopathic GIN. Infection is considered to be the main causative factor of GIN in renal allografts. This paper describes rare cases of GIN that had no infectious episode in the renal allografts.