[Localised Urothelial Carcinoma of the Upper Urinary Tract: Histopathology, Molecular Genetics, and Clinical Features].

Localised upper tract urothelial carcinoma (UTUC) presents a diagnostic challenge due to its biological heterogeneity and anatomical complexity. Early detection and precise risk stratification are crucial for improved prognosis. The combination of histology, urine cytology, and biopsy plays a central role in preoperative diagnosis. Histopathological analysis allows for the determination of tumour grade, with the distinction between low-grade and high-grade tumours being particularly important. Urine cytology demonstrates high specificity for high-grade tumours, but limited sensitivity for low-grade lesions. Molecular markers such as FGFR3 and TP53 mutations, as well as microsatellite instability (MSI) in Lynch syndrome, can contribute to risk stratification and assessment of tumour behaviour. Endoscopic resection represents an effective organ-preserving therapy, particularly for non-invasive tumours. Despite higher recurrence rates compared with radical nephroureterectomy (RNU), it can be a valuable option for patients with chronic renal insufficiency given its organ-sparing approach. However, close follow-up is essential to detect recurrences early.