Giant Pelvic Cyst Mimicking a Para-Ovarian Cyst: A Diagnostic Challenge With Successful Surgical Excision and...

Mesenteric and paratubal cysts are uncommon benign cystic lesions of the abdomen and pelvis that may pose a considerable diagnostic challenge because of their nonspecific presentation and overlapping radiological features. Large pelvic cysts may closely resemble ovarian, paraovarian, or mesenteric lesions, making preoperative diagnosis difficult. We report the case of a 30-year-old woman presenting with a progressively enlarging pelvic-abdominal cyst associated with lower abdominal pain, weakness, and weight loss. Sequential ultrasonography, magnetic resonance imaging, and contrast-enhanced computed tomography demonstrated a large benign-appearing cystic lesion but failed to determine its exact origin. Exploratory laparotomy performed jointly by the gynecology and general surgery teams revealed a giant pelvic cyst densely adherent to the sigmoid mesentery, left ovary, and left fimbrial end, strongly suggesting a mesenteric origin intraoperatively. Complete excision with left fimbriectomy was performed while preserving the bowel and ovary. Histopathological examination demonstrated a benign paratubal cyst with an attached normal fallopian tube, highlighting the importance of histopathological correlation in complex pelvic cystic lesions. This case emphasizes the limitations of imaging and operative assessment in determining the true origin of large pelvic cysts and underscores the role of complete surgical excision in both diagnosis and treatment.