Abstract
INTRODUCTION: Local recurrence for upper tract urothelial carcinoma typically occurs within 2 years post-surgery. We report a rare case of retroperitoneal recurrence as squamous cell carcinoma 10 years after nephroureterectomy. CASE PRESENTATION: A 67-year-old female was referred to our urology department for a left ureteral tumor. The surgical specimen of the laparoscopic left nephroureterectomy revealed urothelial carcinoma at the pT3 stage. Ten years post-nephroureterectomy, magnetic resonance cholangiopancreatography revealed a mass lesion in the left retroperitoneum, a computed tomography-guided biopsy revealed squamous cell carcinoma. Despite suspected distant metastases of other organ tumors, examinations such as digestive endoscopy and bronchoscopy did not reveal any tumor lesions. The patient was diagnosed with recurrent invasive urothelial carcinoma as a pathological feature of squamous cell carcinoma. CONCLUSION: The decision-making process for treating malignant tumors, such as in cases with recurrence as squamous cell carcinoma, can be challenging.