Non-syndromic Multifocal Low-Grade Oncocytic Renal Tumors, Including Microtumors, in End-Stage Renal Disease Kidneys with Synchronous Non-TSC Renal Cell Neoplasms.

This article focuses on low-grade oncocytic tumor (LOT), a recently recognized indolent renal neoplasm frequently harboring mutations in the TSC/MTOR signaling pathway, and its occurrence in patients with end-stage renal disease (ESRD) or chronic kidney disease (CKD) independent of tuberous sclerosis complex (TSC). The authors report four patients with multifocal LOTs, including microtumors, coexisting with other ESRD-associated renal neoplasms such as acquired cystic disease-associated renal cell carcinoma (ACD-RCC) and clear cell papillary renal cell tumor (CCPRCT), none of whom exhibited clinical or genetic features of TSC. This series highlights that multifocal LOTs can arise sporadically in the ESRD setting, often alongside other renal tumors, suggesting a distinct pathogenic pathway linked to the uremic microenvironment rather than hereditary syndromes. Recognition of LOT in this clinical context is important to avoid misdiagnosis and overtreatment.