後腹膜穆勒氏囊腫於六年間由13公分增長至27公分之進行性增大：病例報告

徐英傑¹、余燦榮¹、陳佳其²

¹義大醫療財團法人義大醫院 泌尿科；

²義大醫療財團法人義大醫院 解剖病理科

Progressive Enlargement of a Retroperitoneal Müllerian Cyst From 13 to 27 cm Over Six Years: A Case Report

Ying-Jie Hsu¹, Tsan-Juang Yu¹, Chia-Chi Chen²

¹Department of Urology, E-Da Hospital, Kaohsiung, Taiwan;

²Department of Pathology, E-Da Hospital, Kaohsiung, Taiwan

Introduction:
Female retroperitoneal Müllerian cysts are rare benign cystic lesions arising from Müllerian-type epithelium in the retroperitoneum. They are often discovered incidentally but may enlarge progressively and cause compressive symptoms. Because imaging findings are nonspecific and can mimic adnexal or other retroperitoneal tumors, a definitive diagnosis usually requires histopathological confirmation.

Case presentation:
A 73-year-old woman with a history of right ureteral urothelial carcinoma (pT1), end-stage renal disease on maintenance hemodialysis (three times per week), and hypertension presented with gross hematuria. Computed tomography revealed suspicious hyperdense lesions in the right mid-ureter with hydroureteronephrosis and an incidental 13-cm cystic lesion in the left retroperitoneal space, initially suspected to be adnexal in origin. She underwent robot-assisted transperitoneal laparoscopic right nephroureterectomy with bladder cuff excision on August 27, 2019; planned concurrent resection of the cystic lesion was deferred due to prolonged operative time. She was followed regularly in the outpatient clinic. Six years later, she developed progressive abdominal distension, constipation, and poor appetite. Follow-up computed tomography demonstrated interval enlargement of the cystic lesion to 27 cm, occupying both the abdominal and pelvic cavities. She subsequently underwent excision of the retroperitoneal tumor. Intraoperatively, a large retroperitoneal cystic mass with adhesions to the descending colon was identified, and the left ovary was preserved. Approximately 3,000 mL of serous fluid was aspirated from the cyst. Histopathological examination confirmed a Müllerian cyst. Her symptoms improved postoperatively, and there was no evidence of recurrence during 1 year of follow-up.

Conclusion:
Retroperitoneal Müllerian cysts should be considered in the differential diagnosis of large retroperitoneal cystic masses in adult women. Given the nonspecific radiologic appearance and uncertainty regarding the lesion’s origin, complete surgical excision with histopathological evaluation provides both definitive diagnosis and effective symptom relief.