Ces Urol 2026, 30(2):67-76 | DOI: 10.48095/cccu2026008

The incidence of molecularly defined renal cell carcinomas in a retrospective cohort from a single urology center

Petr Stránský jr.¹, Jiří Kolář¹, Tomáš Pitra¹, Jan Pernický², Taťána Bryndaková³, Ondřej Fiala^4,5, Milan Hora¹, Petr Stránský¹, Michal Michal^3,6, Ondrej Ondič^3,6, Kristýna Pivovarčíková^3,6

¹ Urologická klinika LF UK a FN Plzeň

² Klinika zobrazovacích metod LF UK a FN Plzeň

³ Šiklův ústav patologie, LF UK a FN Plzeň

⁴ Onkologická a radioterapeutická klinika LF UK a FN Plzeň

⁵ Biomedicínské centrum, LF UK Plzeň

⁶ Bioptická laboratoř, s. r. o., Plzeň

Main statement of the study: Retrospective evaluation of a cohort of 18 patients with molecularly defined renal cell carcinoma at University Hospital Pilsen between January 2018 and September 2025.

Summary: Aim: To evaluate the frequency of molecularly defined renal cell carcinomas (RCC) in a retrospective cohort of patients from a single urology center.

Patients and methods: All patients diagnosed with a renal neoplasm at the Department of Urology, University Hospital Pilsen, between January 2018 and September 2025 were retrospectively identified. Particular attention was paid to cases that underwent diagnostic genetic testing. Ultimately, patients with a confirmed “molecularly defined RCC” were included. Clinical data, tumor type, stage, and disease course were evaluated.

Results: Of a total of 1,589 renal tumors, molecular-genetic testing was performed in 73 cases. A “molecularly defined RCC” was identified in 17 patients (23.29% of those molecularly tested; 1.2% of all tumors). The most frequent entity was TFE3-rearranged RCC (N = 9), followed by fumarate hydratase-deficient RCC (N = 4), ELOC-mutated RCC (N = 2), TFEB-amplified RCC (N = 1), and succinate dehydrogenase-deficient RCC (N = 1). A proportion of patients presented with advanced-stage disease. In addition, one case of RCC with fibro(leio)myomatous stroma, an emerging entity according to the current WHO classification, was identified.

Conclusion:  Molecularly defined RCCs accounted for 1.2% of all renal tumors and represented a heterogeneous group dominated by TFE3-altered RCCs, with a frequent occurrence of advanced stages. Molecular-genetic testing confirmed this tumor type in 23.29% of targeted cases. Our data confirm that systematically indicated genetic testing is crucial for accurate classification, has a direct impact on prognosis, and is expected to be important for the selection of appropriate systemic therapy in the future. The results of this study highlight the necessity of accessible and systematically indicated molecular testing of suspected renal tumors as an integral part of modern diagnostic practice.

Keywords: ELOC-mutated renal cell carcinoma – fumarate hydratase-deficient renal cell carcinoma – molecularly defined renal cell carcinoma\\\\r\\\\n– TFEB-altered renal cell carcinoma – TFE3-rearranged renal cell carcinoma

Received: February 10, 2026; Revised: April 6, 2026; Accepted: April 7, 2026; Prepublished online: April 10, 2026; Published: June 22, 2026