Mesenteric cyst is a rare intra-abdominal tumor with prevalence of about 1:20,000 in pediatric age group. Chylolymphatic cysts are rare variants of mesenteric cysts; they account for 3 to 9.2% of all pediatric lymphangiomas [2].

They are benign cystic pathology lined with a thin endothelium or mesothelium that occurred due to gross proliferation of isolated or ectopic lymphatics in mesentery that lack communication with the rest of the lymphatic system. The accumulation in these channels results from an imbalance between the inflow and outflow of fluid [1]. They can occur in any part of the mesentery of the gastrointestinal tract but most commonly are localized in the mesentery of the small intestine, large intestine, and retroperitoneum. They can be single or multiple and unilocular or multilocular and can have serous, chylous, hemorrhagic, or mixed fluid [4]. Our case had a single multilocular chylolymphatic cyst in the mesentery of proximal jejunum.

Based on their etiology, Beahrs et al. [2] classified mesenteric cysts into embryonic or developmental, traumatic, or acquired, neoplastic, or non-neoplastic and infective or degenerative. Based on their contents, mesenteric cysts can be divided into serous, chylous, hemorrhagic, and chylolymphatic cyst. Regarding pathology, mesenteric cysts are classified into four types including type 1 (pedicled) and type 2 (sessile), which are limited to the mesentery, hence can be excised completely with or without resection of the involved gut. Type 3 and type 4 are multicentric, so they require complex surgery and often sclerotherapy because of their extension into retroperitoneum [3]. This case is type 2 (sessile) chylolymphatic cyst.

Most of mesenteric cysts may present as asymptomatic abdominal mass or incidental finding on imaging or laparotomy for other abdominal conditions. In rare occasions, mesenteric cysts may cause acute abdomen from cyst rupture, infection, hemorrhage, intestinal obstruction, and volvulus [5]. In our case, a large chylolymphatic cyst presented as acute intestinal obstruction.

Preoperative diagnosis of mesenteric cyst in most cases is difficult as they have no definite characteristic features. Abdominal ultrasound which is the imaging modality of choice can reveal mesenteric cysts as cystic tumors [6]. Plain X-ray abdomen may show gasless, homogenous mass displacing bowel loops. Multiple air fluid levels may be seen in erect film [5]. Computed tomography can be also used to confirm the diagnosis [3]. In our case, preoperative plain radiograph revealed multiple air fluid levels due to compression and inflammatory adhesion caused by a large multilocular chylolymphatic cyst. Postoperative diagnosis is confirmed with histopathology, which can differentiate the chylolymphatic cyst from other mesenteric cysts [3].

Surgical removal of the cyst is the standard treatment for chylolymphatic cysts. The cyst is removed along with the adjacent bowel loop. Enucleation and cyst drainage were two more techniques mentioned [7]. We just remove the cyst in our case.