Giant Cystic Lymphangioma of the Transverse Mesocolon in a 7-Year-Old Child: A Case Report.

Background: Cystic lymphangiomas are rare benign lymphatic malformations that are usually diagnosed in early childhood. Intra-abdominal lesions are uncommon, and involvement of the transverse mesocolon is particularly rare. Case Presentation: A 7-year-old girl presented with a 3-4 week history of vomiting, abdominal pain, progressive abdominal distension, poor appetite, abdominal fullness, generalized weakness, and irregular bowel movements. Examination revealed a large, well-defined, irregular, non-tender abdominal mass measuring approximately 12 × 10 x 12 cm and extending from the right flank to the pubic region. Laboratory investigations were unremarkable. Preoperative imaging demonstrated a large multiloculated cystic intra-abdominal mass, initially interpreted as an ovarian cyst, but the precise site of origin was not established. Exploratory laparotomy identified a giant multiloculated cystic lesion arising from the transverse mesocolon and extending toward the greater curvature of the stomach. Complete excision was achieved without bowel resection. Histopathological examination confirmed cystic lymphangioma. Recovery was uncomplicated, and no recurrence was observed during 8 months of follow-up. Conclusion: Mesocolonic cystic lymphangioma should be considered in the differential diagnosis of a large multiloculated intra-abdominal cystic mass in a child, including an older child, even when imaging suggests an adnexal lesion. This case highlights the difficulty of determining the site of origin of very large cystic lesions preoperatively and supports complete excision when technically feasible for definitive diagnosis and local disease control.