Abstract
Retroperitoneal lymphangioma is an uncommon and benign mesodermal tumour that arises from the retroperitoneal lymphatics. Notably, it is a rare occurrence in adults, where <200 adult retroperitoneal lymphangioma cases have been published in the literature. Additionally, retroperitoneal lymphangioma is often difficult to diagnose preoperatively and formal diagnosis is frequently determined following surgical exploration. Here, we describe a rare case of retroperitoneal lymphangioma in a 74-year-old man who presented with a 6-month history of intermittent fresh per rectal bleeding with an incidental non-tender left iliac fossa firm mass on examination. Computed tomography scan established a retroperitoneal cystic lesion abutting the aorta and left common iliac vessels. Surgical exploration revealed a large cystic mass and a clean plane of dissection was performed, where the mass was completely excised with all the key structures preserved. Histology was consistent with a retroperitoneal lymphangioma.