Shifts in Diagnostic Practices and Histopathological Profiles of Renal Tumors During the COVID-19 Pandemic: A Single-Center Retrospective Study

Background: The COVID-19 pandemic disrupted healthcare services worldwide, potentially affecting diagnostic and therapeutic approaches to renal tumors. This study aimed to compare the demographic characteristics, diagnostic procedures, and histopathological features of renal lesions before and during the pandemic. Methods: This retrospective, single-center study included 1780 renal lesions submitted for histopathological examination at a tertiary referral institution in Serbia between September 2016 and September 2023. Cases were divided into pre-pandemic (n = 809) and pandemic (n = 971) groups. Demographic characteristics, tumor laterality, diagnostic and surgical procedures, histopathological diagnoses, and selected pathological parameters of different types of renal cell carcinomas (RCCs) were compared. Results: The distribution of diagnostic and surgical procedures differed significantly between the two periods (p < 0.001), with the proportion of percutaneous core needle biopsies increasing from 5.3% to 11.3%. The overall distribution of histopathological diagnoses also differed significantly (p < 0.001), primarily reflecting lower proportions of low-grade RCC (4.2% vs. 1.8%; adjusted p = 0.0347) and other benign epithelial and mesenchymal tumors (4.8% vs. 2.3%; adjusted p = 0.0489). Among the major RCC subtypes, no statistically significant differences were observed in nuclear grade distribution (p = 0.069), pathological tumor stage (p = 0.358), or tumor size (p = 0.412). Patients in the pandemic period were slightly older than those in the pre-pandemic period (median age: 63 vs. 62 years; p = 0.040). Conclusions: The pandemic period was associated with significant changes in the distribution of diagnostic procedures and selected histopathological diagnoses, without a demonstrable shift toward more advanced pathological stages among the evaluated RCC cases. These findings highlight the importance of considering changes in diagnostic pathways and case selection when interpreting renal tumor characteristics during periods of healthcare disruption.