Diagnostic Dilemma of a Giant Paratubal Cyst in an Adolescent Female Mimicking a Mesenteric Cyst: A Case Report.

Paratubal cysts are rare adnexal masses that arise from the mesosalpinx and are typically small and asymptomatic. Giant paratubal cysts are a rare entity and a diagnostic challenge, especially in adolescents, due to nonspecific presentation and radiological similarity to other intra-abdominal cystic masses. A 15-year-old female presented with progressive abdominal distension and mild, nonspecific abdominal pain of three months' duration, associated with recent menstrual irregularities. Physical exam showed a distended, non-tender abdomen. Imaging studies, including computed tomography (CT) and magnetic resonance imaging (MRI), revealed a huge cystic abdominopelvic lesion of around 30 cm displacing the adjacent loops of bowel and showing right-sided hydroureteronephrosis. The origin of the cyst was uncertain, and differential diagnoses were mesenteric cyst and adnexal cyst. Laboratory investigations, including tumor markers, were within normal limits. Laparoscopic exploration was carried out, and a large cyst arising from the left fallopian tube was seen. Approximately 4.6 L of clear fluid was aspirated, followed by complete cyst excision with left salpingectomy. Histopathological examination showed a benign serous cystadenoma with no evidence of malignancy. The patient was well in the follow-up and postoperative period. Giant paratubal cysts are uncommon in the adolescent population and are often misdiagnosed preoperatively because imaging features overlap with ovarian and mesenteric cysts. Most are benign despite their size, but surgical excision is advised because of risks of complications such as torsion, rupture, and pressure effects on nearby organs. With adequate expertise, minimally invasive approaches can be safely performed with reduced morbidity and a faster recovery, even with such a large cyst.