Huge pelvic retroperitoneal cyst masquerading as hydrosalpinx: A case report with review of the literature.

Primary retroperitoneal cysts (RPCs) are a rare surgical entity and are mostly detected incidentally. Usually, they are asymptomatic. At times, they may attain a huge size and may present with a large abdominal lump. Often, they pose a dilemma at diagnosis and for management. Though the laparoscopic approach has been described for their surgical excision, open surgery is still the preferred approach. We herein present a case of a voluminous retroperitoneal pelvic cystic mass in a 40-year-old female, which was diagnosed as hydrosalpinx on a magnetic resonance imaging scan. The patient was referred to us by the specialist in gynecologic laparoscopy after the incidental discovery of the RPC during his surgical intervention, purportedly for large hydrosalpinx. At our hospital, 4 days after the above intervention, she underwent laparoscopic complete excision of the cyst. Her postoperative recovery was uneventful and she was discharged on postoperative day 3 without any complications. Histopathology was suggestive of Mullerian inclusion cyst. This case report aims to share a rare case of a large primary retroperitoneal pelvic cystic lesion, which caused a diagnostic challenge preoperatively but was eventually managed successfully, laparoscopically.