Non-pancreatic Pseudocyst Presenting as a Giant Retroperitoneal Mass

Objective: To assess the non-pancreatic retroperitoneal pseudocyst in the differenctial diagnosis of retroperitoneal cystic masses. Methods: To report a case.Results: We present a case of a 50-year-old woman with symptoms of pain and a palpable abdominal mass. In imaging studies a 13-cm retroperitoneal cystic mass with left ureterohydronephrosis was observed. Surgical excision of the mass was performed with pathological diagnosis of non-pancreatic retroperitoneal pseudocyst.Conclusion: Non-pancreatic retroperitoneal pseudocyst is an entity with a very low incidence, benign, usually asymptomatic. It can grow compressing on adjacent structures. The definitive diagnosis is histopathological and the treatment is surgical. It's important to carry out complete exeresis to avoid recurrences.