Symptomatic Müllerian cyst in the retroperitoneum of an adult male: Case report and review of the literature

Retroperitoneal cysts of Müllerian origin are quite uncommon, and most of the cases reported in the literature are in females. This report details the case of a 20-year-old male who presented with recurrent right flank pain and right flank swelling. Imaging investigations revealed a simple cyst posterior to the right kidney. He subsequently had retroperitoneal exploration and excision of an ovoid cystic mass which was histologically confirmed as a Müllerian cyst. Thus, Müllerian cyst should be kept in mind in the differential diagnosis of retroperitoneal cysts.