Retroperitoneal Pelvic Cyst: A Diagnostic and Therapeutic Challenge

Background: Retroperitoneal cysts can be asymptomatic or can present with vague symptoms such as abdominal pain or distension. Their clinical implications vary significantly. Case: A 45-year-old woman, gravida 2, para 2, presented with vague, non-specific pelvic symptomatology. Imaging indicated a right-sided pelvic cyst 5 cm in diameter. At laparoscopy a retroperitoneal cyst was identified, with a normal pelvis and intra-abdominal organs. No attempt was made at laparoscopy to drain, biopsy, or excise the cyst. CT-guided biopsy of the cyst was performed and small intestine mucosa was identified with goblet cells and smooth muscle. Repeat biopsy confirmed areas of tissue necrosis and small intestine mucosa, with additional tissue containing respiratory epithelium. Following laparotomy and excision of the cyst, the final pathologic diagnosis was benign epithelial cyst consistent with a duplication or hindgut cyst. Conclusion: Although most retroperitoneal cysts are benign, surgical excision is required to rule out malignancy definitively.