Abstract
Intra-abdominal cystic lymphangioma (ACL) is an uncommon cystic tumour of the abdomen and is considered a rare subtype of lymphangioma. These cystic tumours are mostly found in children, and the lesions are the result of an underdeveloped lymphatic system. Patients may have persistent abdominal pain and a noticeable abdominal mass. Non-invasive imaging, such as an ultrasound, as well as computed tomography scan can confirm the presence of a mass, but the final diagnosis is obtained through histopathological examination. Given the rare nature of ACL, there is limited information available, but the available literature suggests that complete surgical treatment is the best management. Searching aggressively will allow an adult patient to resolve the problem of this underreported disease in a more effective and timely manner. LEARNING POINTS: Retroperitoneal cystic lymphangiomas are an exceptionally rare subset of benign lymphatic malformations in adults, often presenting with vague and nonspecific abdominal symptoms that complicate early recognition.This case of a 30-year-old male with retroperitoneal cystic lymphangioma underscores the diagnostic challenges, particularly when routine endoscopic and laboratory evaluations are unremarkable whereby contrast-enhanced computed tomography imaging proved pivotal in localizing and characterizing the lesion, informing surgical planning.This case highlights the necessity of maintaining a high index of suspicion for retroperitoneal cystic lymphangiomas in adults presenting with unexplained abdominal pain and reinforces the critical role of imaging and surgical management in achieving favourable outcomes.