Pyogranulomatous cystitis associated with Toxoplasma gondii infection in a cat after renal transplantation

CASE DESCRIPTION: An 8-year-old spayed female domestic shorthair cat was evaluated for azotemia and a suspected mass in the urinary bladder 6 weeks after receiving a renal transplant. Ultrasonography revealed a mass at the ureteroneocystostomy site, and the mass was excised. Both the donor and recipient cats were seronegative for Toxoplasma gondii-specific IgG antibodies prior to transplantation. CLINICAL FINDINGS: Histologic evaluation of the mass revealed lesions indicative of extensive necrotizing pyogranulomatous cystitis with numerous intralesional T gondii tachyzoites and bradyzoite cysts. TREATMENT AND OUTCOME: Treatment with clindamycin was initiated; however, the cat's clinical condition continued to decline, and it was euthanized 9 days after the mass was excised. Necropsy revealed T gondii cysts within the renal allograft and the transplanted ureter, with no evidence of systemic spread of organisms. CLINICAL RELEVANCE: Toxoplasmosis should be considered as a differential diagnosis for azotemia in feline renal transplant recipients regardless of the results of assays for T gondii antibodies in the serum of donors or recipients. This report illustrated the need for improved screening of donor and recipient cats and the importance of minimizing exposure to potential sources of T gondii after transplantation.