Urachal Adenocarcinoma with Bone and Lung Metastases: A Rare Case Report and Literature Review
Huang-Yi Chien, Chun-Hou Liao
Department of Urology, Cardinal Tien Hospital, New Taipei City, Taiwan
Background: Urachal carcinoma is a rare malignancy accounting for 0.34-0.7% of all bladder carcinomas. Urachal carcinoma stems from the epithelium of the remnant of urachus, and adenocarcinoma accounts for 90% of all cases. Urachal adenocarcinoma has been regarded as associated with poor prognosis, especially in the case of urachal mucinous adenocarcinoma. Surgery remains the primary treatment for prolonging the overall survival time of patients. However, no standard chemotherapy or immunotherapy for advanced urachal carcinoma have yet been established. We report a case of urachal adenocarcinoma with bone and lung metastases.
Case: In 2020/09, a 69-year-old female without systemic underlying disease presented with gross hematuria and dysuria, then visited our hospital for help. KUB showed no obvious urolithiasis formation. Renal ultrasound showed no tumor-like lesion or hydronephrosis. Cystoscopy demonstrated a large protruding tumor with fluffy surface at bladder dome. Computed tomography reported a 5.4cm calcified mass over bladder dome and bilateral iliac lymphadenopathy. After that, transurethral resection of bladder tumor (TURBT) was done. However, pathology reported adenocarcinoma. Lab examination revealed normal value of CEA/CA-125/CA-153 but elevated value of CA-199(344.65U/mL). After discussion, she underwent partial cystectomy with bilateral pelvic lymph node dissection and umbilicus resection on 2020/10/07. Pathology reported urachal adenocarcinoma, mixed mucinous type, involved bilateral pelvic lymph nodes (Left 5/5, Right 1/5). Because poor-healing of bladder anastomosis, she was discharged without Foley after 1 month admission. However, follow-up computed tomography showed multiple right iliac lymphadenopathy. Whole body bone scan revealed highly suspected bone metastasis over left 5th rib. Oncologist was then consulted for further adjuvant therapy. In 2020/12, she underwent radiotherapy to right iliac lymphadenopathy. Cisplatin-based chemotherapy was not feasible due to impaired renal function (Ccr:53.1mL/min). During 2020/12 to 2021/6, she received 6 cycles of Carboplatin + Gemcitabine (every 4 weeks). Lab examination showed decreased CA-199(144.15U/mL). However, follow-up computed tomography in 2021/7 revealed recurrent tumor over right lateral wall of bladder, lung metastases, enlarged right iliac lymphadenopathy and paraaortic lymphadenopathy. Whole body bone scan reported enlarged left 5th rib bone metastasis. During 2021/9 to 2021/12, she received total 5 cycle of Nivolumab (every 4 weeks). However, progression disease in lung, retroperitoneum and pelvis was reported in follow-up image. After discussion with families, she underwent palliative care. Finally, she passed away in 2022/2 (16 months after diagnosis).
Discussion: The urachus is a fibrous allantoic remnant that connects the bladder to the umbilical cord during embryogenesis. After birth, the lumen of the urachus is usually obliterated. However, an autopsy series has found that urachal remnant persists as a tubular or cystic structure in the dome and elsewhere along the midline of the bladder in one third of adults. The carcinoma of the urachus is a rare and aggressive malignant tumor affecting mostly men in the V–VI decade of age (male:female=1.4~1.6:1). Patients usually present with hematuria, abdominal pain, irritative symptoms, mucusuria, palpable suprapubic mass and umbilical discharge. The estimated 5-year survival rate does not reach the 50%. On average, 11–13% of patients are reported as metastatic at disease presentation. Since urachal carcinoma needs to grow sufficiently large enough to become symptomatic, delayed clinical diagnosis may explain the poor prognosis of this disease. It is difficult to differentiate urachal from non-urachal bladder adenocarcinoma because of the overlapping histologic and immunohistochemical features. The diagnostic criteria of urachal adenocarcinoma include tumors located in the bladder dome, a sharp demarcation between the tumor and the surface epithelium, and the exclusion of adenocarcinoma of other organs that has spread secondarily to the bladder. The standard of primary treatment for localized disease is en-bloc resection of the bladder dome, urachal ligament, and umbilicus. Despite surgical improvements, urachal adenocarcinoma has a high recurrence rate (20%–38%). Most common sites of recurrence are the pelvis (37%), bladder (34%), lungs (28%), and lymph nodes (18%). Due to the similarity of urachal cancer to colorectal adenocarcinoma and urothelial carcinomas, treatment regimens used for metastatic disease are often the same. Some reports recommend Cisplatin plus 5-FU, FOLFOX, Gemcitabine plus Cisplatin, MVAC, or other immunotherapy. However, the number of cases is low, and there are no sufficient evidence-based indication that can guide chemotherapy and immunotherapy. No significant survival difference was found between patients with lymph node metastases compared to those with distant organ metastases
Conclusion: Urachal adenocarcinoma is a rare tumor that can progress and metastasize rapidly. Because of lack of early symptoms, delayed diagnosis is one of possible reason for poor prognosis. Limited evidence due to rarity of disease is available to guide clinician in diagnosis and treatment. Surgery is the main treatment of choice for localized urachal adenocarcinoma. However, there are no standard surgical treatment (partial cystectomy or radical cystectomy), chemotherapy nor immunotherapy for advanced urachal adenocarcinoma.