Mesenteric cysts are one of the rarest abdominal tumors, with a reported incidence of 1 case per 100,000 to 250,000 admissions. Approximately 820 cases have been reported since 1507, when Beneviene first described them during the autopsy of a child [1, 7, 8]. They can occur at any age, with a peak incidence in the fourth decade of life [8].

The etiology is still unknown. Some authors believe they arise from the continuous growth of congenital malformations or ectopic lymphatic tissues, while others suggest that they are a developmental anomaly secondary to trauma, degeneration of lymph nodes, lymphatic vessel obstruction, or abnormal fusion of the mesentery layers. This variability in proposed etiological theories may be because it is a multifactorial phenomenon [1, 8]

Perrot et al. described a classification based on histopathological characteristics, which includes the following 6 groups: (1) lymphatic origin cysts (simple lymphatic cyst and lymphangioma); (2) mesothelial origin cysts (simple mesothelial cyst, benign cystic mesothelioma, and malignant cystic mesothelioma); (3) enteric origin cysts (enteric cyst and intestinal duplication cyst); (4) urogenital origin cysts; (5) mature cystic teratoma (dermoid cyst); and (6) non-pancreatic pseudocysts (of traumatic or infectious origin) [8].

From a pathological point of view, mesenteric cysts vary in size and shape, ranging from a few centimeters to a size that occupies most of the abdominal cavity, with sizes ranging from 2 to 35 cm [8]. They can be single or multiple, unilocular or multilocular. The content varies from serous to chylous or deep brown, depending on the location and the presence or absence of hemorrhage [1, 7]. Microscopically, these cysts have a lining of fibrous tissue or a single layer of endothelial cells. Wall calcification is unusual.

Mesenteric cysts can vary in their location, from the duodenum to the rectum. However, 50% of them are located in the small intestine, and 25% of those are in the ileal mesentery [7]. Malignant forms have been reported with an incidence of less than 3% [1], most of them were sarcomas, and some reported cases were adenocarcinomas [8].

The clinical presentation is highly variable, with no pathognomonic signs or symptoms, and is dependent on various factors: cyst size, location, and presence or absence of complications. Three forms of presentation can be described:

1)

Asymptomatic (40–45%): Diagnosis is generally using imaging or surgical findings;

2)

Nonspecific abdominal symptoms: This includes abdominal pain and distension, occasionally associated with nausea, vomiting, diarrhea, constipation, and weight loss;

3)

Acute abdomen (30%): Arises secondary to complications of the cyst, which can include obstruction (due to compression of adjacent intestines), volvulus (which can progress to gangrene, peritonitis, and shock), hemorrhage (secondary to trauma and erosion), infection, or rupture of the cyst.

The most common symptom is abdominal pain (55–82%), followed by the presence, upon physical examination, of a palpable abdominal mass that is smooth, rounded, and compressible (55–61%), and abdominal distension (17–61%) [7, 8].

The non-specificity of the clinical presentation makes the diagnosis of a mesenteric cyst challenging. In addition, laboratory results do not contribute to the diagnosis. There are no specific radiological signs. However, ultrasound and computed tomography (CT) are considered the two most useful complementary studies [1]. Both show the cystic nature of the lesion, the absence of connection of the cystic mass with other organ structures, the presence of internal septa, and the thickness of the wall. Compared to ultrasound, CT provides greater certainty in determining the nature of the cystic content. The MRI has higher accuracy in determining the topographic location of the cyst as well as its content [8].

The standard treatment for mesenteric cysts is complete surgical enucleation. Other procedures such as aspiration and marsupialization are not recommended as they are associated with a high recurrence rate and risk of infection. In cases of malignant cysts, acceptable cure rates were reported following enucleation with clear margins. It is worth mentioning that, depending on the involvement of the neighboring structures, an intestinal resection followed by a small intestinal anastomosis may be necessary for cyst resection. The laparoscopic surgical approach should be adopted, only resorting to the conventional approach for cases with technical difficulty due to the location and/or size of the lesion.