Urothelial carcinomas in renal transplant recipients usually occur in the native urinary tract but rarely in the renal allograft. We describe FDG PET/CT and contrast-enhanced CT findings in a case of high-grade urothelial carcinoma arising within the renal allograft with lymph node metastases 9 years after renal transplantation. The primary tumor appeared as an FDG-avid heterogeneously enhancing renal mass with poorly defined margins and preservation of the reniform shape mimicking centrally located infiltrative renal cell carcinoma. Multiple FDG-avid inhomogeneously enhancing ipsilateral internal and external iliac, and retroperitoneal lymph node metastases were observed.

Background Wilms' tumor (WT) is the most common pediatric renal malignancy (~90% of childhood kidney tumors). Survival exceeds 90% in high-income countries, but data from low-resource settings are limited. This study describes the demographic distribution, clinical presentation, management patterns, and short-term outcomes of pediatric WT in Sana'a, Yemen. Methods This prospective study (January 2021-December 2022) included children ≤15 years with Wilms' tumor diagnosed by clinical assessment, radiological imaging (abdominal ultrasound and contrast-enhanced CT and chest CT to assess local tumor extension and the presence of distant metastases), and histopathological confirmation following surgical resection. Demographic, clinical, radiological, surgical, and pathological data were prospectively collected using a standardized case report form. Tumors were staged according to the Children's Oncology Group (COG) criteria, and treatment modalities and short-term outcomes were evaluated. Results Fourteen pediatric WT patients (n = 14) were identified, with male predominance (71.4%) and a mean age of 3.6 ± 3.5 years. Abdominal mass was the most common presentation (85.7%). By COG staging: Stage I (35.7%), Stage II (50.0%), Stage III (14.3%); all had favorable histology (100%). Preoperative chemotherapy was given to 28.6%, all underwent surgical resection (100%), postoperative chemotherapy to 21.4%, and none received radiotherapy. At a median follow-up of 15 months (range 7-22), complete remission occurred in 92.9% (13/14), while one patient (7.1%) relapsed and died at 18 months. Conclusion Pediatric WT in this Yemeni cohort presented at an early stage with favorable histology; despite limited chemotherapy use and the absence of radiotherapy, short-term remission rates were favorable. Longer follow-up and improved multimodal therapy are needed.

This review focuses on intravesical recurrence (IVR) of upper tract urothelial carcinoma (UTUC).