Podium 01
蔡政軒、梁柏崧、陳俊吉
彰化基督教醫院 外科部 泌尿科
Cheng-Hsuan Tsai, Po-Sung Liang, Chun-Chi Chen
Divisions of Urology, Department of Surgery, Changhua Christian Hospital, Changhua, Taiwan
Retroperitoneal endometriosis is a rare clinical entity, particularly in patients with a remote history of total hysterectomy. We present a 47-year-old female with a history of cervical cancer (s/p total hysterectomy 20 years ago) who presented with left flank pain and hydronephrosis. Initial MRI suggested a large clustered lobulated mass (10.5 cm * 6.9 cm) in the bilateral anterior pararenal space, leading to an impression of retroperitoneal lymphangioma. However, following 3D laparoscopic cyst unroofing, histopathology confirmed bilateral retroperitoneal endometriomas (PAX-8+, ER+, CD10+, D2-40-). This case highlights the diagnostic challenge of extragenital endometriosis and its potential to cause significant obstructive uropathy decades after gynecological surgery.
Endometriosis is defined as the presence of functional endometrial tissue outside the uterine cavity. While pelvic involvement is common, retroperitoneal endometriosis is rare and often asymptomatic until it causes compression of adjacent organs [1]. Ureteral involvement occurs in only 0.1% to 1% of endometriosis cases, potentially leading to silent but progressive renal failure [2]. The occurrence of symptomatic retroperitoneal endometrioma 20 years after a total hysterectomy is exceptionally rare and may mimic other retroperitoneal cystic neoplasms.
A 47-year-old female with a history of cervical cancer (s/p total hysterectomy 20 years ago), hypertension, and hyperthyroidism presented with left flank pain in October 2025.
● Imaging & Diagnosis: MRI revealed a clustered lobulated mass in the bilateral anterior pararenal space (up to 10.5 cm * 6.9 cm), containing cystic components and potential blood clots. The mass compressed the left ureter, causing hydronephrosis. The initial radiological impression was retroperitoneal lymphangioma.
● Management: Due to acute fever and infection, a double-J stent was inserted for decompression. The patient then underwent 3D laparoscopic retroperitoneal cyst unroofing. Intraoperatively, brownish, elastic tissue fragments were identified.
● Pathology: * Gross: Right specimen ($5 \times 2$ cm) and Left specimen ($4.5 \times 2$ cm) were both brownish and elastic.
○ Microscopy: Cystic structures lined by ectopic endometrioid epithelial lining and stroma cells with aggregates of hemosiderin-laden macrophages.
○ IHC Study: Positive for PAX-8, ER, and CD10 (stroma). Notably, D2-40 (lymphatic endothelium marker) was negative, definitively ruling out lymphangioma.
The pathogenesis of endometriosis after hysterectomy remains debated; theories include coelomic metaplasia or the persistence of microscopic foci from previous surgery stimulated by residual ovarian function [3]. In this case, the 20-year latency period and the massive size of the lesions (>10 cm) are particularly striking.
Radiologically, retroperitoneal lymphangiomas and endometriomas can appear remarkably similar on MRI as multiloculated cystic masses. However, the presence of internal "blood clots" or "shading signs" on T2-weighted images often suggests the hemorrhagic nature of an endometrioma [4]. This case is unique as the bilateral distribution and location in the pararenal space strongly mimicked a lymphatic malformation.