Robotic Partial Cystectomy and Extended Pelvic Lymph Node Dissection for Node-Positive Urachal Adenocarcinoma in a 34-Year-Old Woman: A Case Report

Urachal carcinoma is a rare and aggressive malignancy for which standardized management remains limited, particularly in patients with locally advanced and node-positive disease. We report the case of a 34-year-old woman with urachal adenocarcinoma involving the bladder dome and radiographically suspicious pelvic lymph nodes who underwent robot-assisted partial cystectomy with urachal resection and extended bilateral pelvic lymph node dissection. Because there was no clinical, radiologic, or intraoperative evidence of umbilical involvement, the umbilicus was preserved after preoperative counseling and intraoperative confirmation of a negative proximal margin. Final pathology demonstrated a 4.5 cm enteric-type urachal adenocarcinoma, pT3a pN2 (2/17), with lymphovascular invasion, perineural invasion, and negative surgical margins. Immunohistochemistry and DNA- and RNA-based next-generation sequencing showed microsatellite stability, mismatch-repair proficiency, low tumor mutational burden, and no actionable genomic alteration. Given the absence of an established adjuvant standard, the multidisciplinary tumor board selected adjuvant FOLFOX as a non-standard postoperative strategy based on the overall clinicopathologic context. The patient remained continent, experienced no postoperative complications or treatment-limiting toxicity, and showed normalization of carcinoembryonic antigen and carbohydrate antigen 19-9 levels. This case provides a carefully contextualized example of transparent surgical reasoning and restrained multidisciplinary management in a rare malignancy with limited prospective evidence.