Renal Neoplasia in Polycystic Kidney Disease: An Assessment of Tuberous Sclerosis Complex-associated Renal Neoplasia and PKD1/TSC2 Contiguous Gene Deletion Syndrome.

To determine the incidence of renal neoplasia among patients undergoing nephrectomy for polycystic kidney disease (PKD), we queried our institutional nephrectomy registry (years 2000-2020). Approximately 4% (231 of 5757) of patients who underwent nephrectomy had PKD, and 26 of these 231 patients (11.3%) had renal neoplasia. Tumors from an additional two patients with PKD were also evaluated. Patients with PKD who had tuberous sclerosis complex (TSC)-associated renal neoplasia were screened for PKD1/TSC2 contiguous gene deletion syndrome (CGS) using single nucleotide polymorphism arrays. The median age of patients with PKD and renal neoplasia at nephrectomy was 54 yr. The median tumor size was 2.0 cm and the tumors were predominantly of low grade and stage. The tumors consisted of 23 renal cell carcinomas (RCCs), one epithelioid angiomyolipoma, and four angiomyolipomas. The median follow-up was 59.5 mo (n = 26) and only one patient with clear cell RCC developed metastases. Two patients with angiomyolipomas had PKD1/TSC2 CGS. Our results support screening of patients with PKD and TSC-associated renal neoplasia as well as TSC patients with cystic renal disease for CGS, as identification of patients with CGS can better define the manifestation and prognosis of CGS and guide counseling regarding patterns of inheritance. PATIENT SUMMARY: We identified patients with abnormal kidney cell growth (called renal neoplasia) among those undergoing removal of kidney tissue for polycystic kidney disease (PKD) and patients with a syndrome involving deletions in two genes, called PKD1/TSC2 contiguous gene deletion syndrome (CGS) at our institution. Of 231 PKD patients with removal of kidney tissue, 11.3% had renal neoplasia, and two patients with angiomyolipoma tumors had PKD1/TSC2 CGS. Detection of renal neoplasia associated with a condition called tuberous sclerosis complex in PKD may increase the identification of patients with PKD1/TSC2 CGS and guide patient counseling regarding outcomes and patterns of inheritance.