De novo renal carcinoma arising in non-functional kidney graft: a national retrospective study

Aim Characteristics of renal carcinoma arising in non-functional graft in renal transplant recipients (RTR) are unknown. We studied a large national retrospective cohort to analyze circumstances of diagnosis, treatment and outcome compared to the literature. Methods Study included all RTR presenting with kidney graft tumors irrespective of the histology, except those with lymphoma and including those tumors arising in non-functional renal graft. Between January 1988 and December 2018, 56,806 patients had renal transplantation in the 32 centers participating in this study. Among this cohort, 18 renal graft tumors were diagnosed in non-functional grafts. Results The median patient age at the time of diagnosis was 42.1 years (31.7-51.3). Median age of kidney grafts at the time of diagnosis was 56.4 (23.2-63.4). Eight (44.4%) tumors were discovered fortuitously on renal graft histologic analysis. Fourteen tumors (77.8%) were papillary carcinomas. Two patients had clear cell carcinomas and one patient had a pTa high-grade multifocal urothelial carcinoma in the graft of the upper tract with an in situ carcinoma. Conclusion Renal carcinomas in non-functional grafts are rare entities and most of them are diagnosed fortuitously. Despite the fact that these tumors are small, low grade and with a good prognosis, regular monitoring of non-functional grafts should be performed with at least an annual ultrasonography.