Giant Mesenteric Cyst: A Case Series

Abstract

Introduction

Mesenteric cysts are rare benign intra-abdominal lesions that can present with a wide spectrum of clinical manifestations. They are most commonly located within the mesentery of the small intestine and are less frequently found in the mesocolon. Because their clinical presentation varies according to the size and location of the cyst, symptoms are often nonspecific, making diagnosis challenging.

Case Presentation

We report two pediatric cases of mesenteric cysts. The first case involved a 10-month-old male infant who presented with abdominal distension and intermittent non-bilious vomiting. The second case involved a 5-year-old boy who presented with severe abdominal distension caused by a large intra-abdominal mass and was subsequently referred to the Pediatric Surgery Department. Following clinical evaluation and preoperative investigations, both patients were diagnosed with mesenteric cysts and underwent surgical excision. The resected cysts were submitted for histopathological examination, which confirmed the diagnosis. Both patients had an uneventful postoperative recovery, with no complications or recurrence observed during follow-up.

Clinical Discussion

Mesenteric cysts are exceedingly rare, with an estimated incidence of approximately 1 per 250,000 hospital admissions. They may occur at any age but are uncommon in children. Most mesenteric cysts remain asymptomatic and are discovered incidentally during radiological investigations or surgical procedures. Clinical symptoms typically develop when the cyst enlarges sufficiently to cause compression of adjacent structures, resulting in abdominal distension, pain, vomiting, or intestinal obstruction.

Conclusion

We present two pediatric cases of mesenteric cysts to highlight the importance of considering this rare entity in the differential diagnosis of abdominal masses and distension in children. Early diagnosis and complete surgical excision remain the cornerstone of successful treatment and are associated with excellent outcomes.

Introduction

Mesenteric cysts are rare, benign cystic lesions that may arise anywhere along the mesentery of the gastrointestinal tract, from the duodenum to the rectum, although most occur within the small-bowel mesentery, particularly the jejunal and ileal mesentery.^1,2 They are encountered far more often in adults than in children, with an overall estimated incidence of approximately 1 in 100,000 to 1 in 250,000 hospital admissions; in infants and young children, mesenteric cysts remain an especially uncommon cause of an intra-abdominal mass.^1,2

The etiology of mesenteric cysts remains incompletely understood. Proposed mechanisms include congenital sequestration or maldevelopment of mesenteric lymphatic channels that fail to establish normal communication with the venous system, and, less commonly, traumatic, infectious, or neoplastic processes.^3,4 Most pediatric mesenteric cysts are now recognized histologically as lymphatic malformations (cystic lymphangiomas), and recent surgical series have proposed classification systems based on cyst location, the number of loculations, and the presence of associated complications such as infection, hemorrhage, or volvulus to help guide surgical planning.^3–5

The clinical presentation of mesenteric cysts is highly variable and depends largely on cyst size, location, and the presence of complications. Smaller cysts are frequently asymptomatic and discovered incidentally, whereas larger or giant cysts more often present with progressive abdominal distension and a palpable mass, sometimes mimicking ascites, an ovarian mass, or other intra-abdominal tumors.^6–8 Reported complications of large mesenteric cysts include compression of adjacent bowel and viscera, intestinal obstruction, volvulus, hemorrhage, infection, and, rarely, rupture or an acute abdomen requiring emergency surgery.^6,8,9

Imaging plays a central role in raising suspicion for a mesenteric cyst and in surgical planning. Abdominal ultrasonography is widely used as the initial investigation because it is non-invasive, inexpensive, and effective at characterizing a lesion as cystic, while contrast-enhanced computed tomography (CT) and, where available, magnetic resonance imaging (MRI) provide more detailed information on the size, extent, and relationship of the cyst to the bowel and major vessels, which is essential for operative planning.^2,10 Despite these advances, a definitive diagnosis is still usually established only after surgical excision and histopathological examination.^2,10

Complete surgical excision remains the cornerstone of treatment, providing both definitive cure and tissue for histopathological diagnosis while minimizing the risk of recurrence.^2,3 When feasible, minimally invasive laparoscopic or robotic-assisted approaches have increasingly been reported, even for relatively large cysts, although open surgery and concomitant bowel resection may still be required when the cyst is densely adherent to, or shares a blood supply with, the adjacent intestine.^3,5 Herein, following the Preferred Reporting Of CasE Series in Surgery (PROCESS) guidelines.¹¹ We present two pediatric cases of giant mesenteric cysts in male patients who presented with progressive abdominal distension and large intra-abdominal masses. Both patients were successfully managed surgically with complete cyst excision and had favorable postoperative outcomes, underscoring the importance of considering this rare entity in the differential diagnosis of pediatric abdominal masses and the central role of timely surgical management.

Case Presentation

Case 1

A 10-month-old male infant presented with progressive abdominal distension and intermittent non-bilious vomiting. Physical examination revealed a palpable abdominal mass associated with a large umbilical hernia. The abdomen was soft, with no tenderness or signs of peritoneal irritation. Routine laboratory investigations were within normal limits.

Abdominal ultrasonography demonstrated a large cystic lesion suggestive of a mesenteric cyst. Contrast-enhanced computed tomography (CT) of the abdomen confirmed the presence of a well-defined, large cystic mass occupying the central portion of the abdominal cavity (Figure 1). Following preoperative evaluation, the patient was scheduled for surgical intervention.

Figure 1.

Contrast-enhanced abdominal ct scan showing a giant mesenteric cyst occupying a large portion of the abdominal cavity and protruding through the umbilical defect, resulting in marked abdominal distension.

Exploratory laparotomy revealed a giant mesenteric cyst arising from the jejunal mesentery, measuring approximately 20 cm in diameter (Figure 2). Due to its close association with the adjacent bowel and mesentery, complete excision of the cyst was performed along with resection of the involved jejunal segment and mesentery (Figure 3). Intestinal continuity was restored by primary end-to-end anastomosis, and the mesenteric defect was repaired. In addition, the associated umbilical hernia was repaired during the same procedure.

Figure 2.

Intraoperative view of a giant mesenteric cyst identified during surgical exploration of the abdominal cavity.

Figure 3.

Excised mesenteric cyst specimen following complete surgical removal during laparotomy.

Histopathological examination confirmed the diagnosis of a mesenteric cyst. The postoperative course was uneventful, and the patient remained asymptomatic with no evidence of recurrence during six months of follow-up.

Case 2

A 5-year-old boy was referred to the Pediatric Surgery Department with severe abdominal distension caused by a large abdominal mass. According to his medical history, the mass had first been noted at the age of three years and was initially associated with episodes of bilious vomiting. Over time, the abdominal swelling gradually increased in size. Echocardiography was performed as part of the preoperative assessment to exclude associated congenital anomalies and revealed no abnormalities.

On physical examination, a large, round abdominal mass occupying almost the entire abdominal cavity was palpable. The mass was soft in consistency with mild tenderness on palpation, and its borders were poorly defined. Laboratory investigations, including liver, pancreatic, and renal function tests, were within normal limits.

Abdominal ultrasonography demonstrated a large cystic intra-abdominal lesion consistent with a mesenteric cyst. Contrast-enhanced CT imaging further revealed a giant cystic mass extending from the region inferior to the stomach down to the pelvic cavity (Figure 4).

Figure 4.

Abdominal ct scan showing a large mesenteric cyst occupying a substantial portion of the abdominal cavity, with marked compression and leftward displacement of the adjacent intestinal loops.

Following appropriate preoperative preparation, the patient underwent exploratory laparotomy. Intraoperatively, a massive cyst arising from the mesentery beneath the stomach was identified (Figure 5). Complete surgical excision of the cyst was achieved without complications, and the specimen was sent for histopathological evaluation.

Figure 5.

Intraoperative view of a giant mesenteric cyst occupying a large portion of the abdominal cavity and arising from the mesentery, identified during exploratory laparotomy.

The postoperative recovery was uneventful. Histopathological examination confirmed the diagnosis of a mesenteric cyst. At six months of follow-up, the patient remained symptom-free, with no evidence of recurrence or postoperative complications.

Discussion

Mesenteric cysts are rare benign intra-abdominal lesions that can arise anywhere along the mesentery of the gastrointestinal tract, from the duodenum to the rectum. Although they may occur at any age, they are markedly less common in children than in adults, and giant mesenteric cysts, generally defined as those exceeding 10 cm in diameter, represent an even rarer subset that has been described mainly through individual case reports and small case series over the past decade.^1,2,7 Because of their rarity and the nonspecific nature of their symptoms, mesenteric cysts continue to pose a diagnostic challenge for pediatric surgeons and radiologists.

The exact pathogenesis of mesenteric cysts remains incompletely defined. The most widely accepted theory attributes their formation to congenital maldevelopment or sequestration of mesenteric lymphatic channels that fail to establish a normal connection with the venous system, producing a lymphatic malformation (cystic lymphangioma); other proposed mechanisms include traumatic, infectious, and degenerative processes.^3,4 Recent surgical series of pediatric mesenteric and omental lymphatic malformations have proposed location-based classification systems, differentiating, for example, cysts of the small-bowel mesentery, colonic mesentery, and those with retroperitoneal extension, to help predict complications and guide the choice of operation.^3,4 The absence of any history of abdominal trauma, surgery, or infection in both of our patients is consistent with a congenital lymphatic origin.

Clinical manifestations of mesenteric cysts depend heavily on their size and location. Small, asymptomatic cysts are often discovered incidentally, whereas giant cysts more typically present with painless, progressive abdominal distension and a large palpable mass, occasionally mimicking ascites or an ovarian or other pelvic mass, particularly in girls.^6–8 In the present series, both children presented with progressive abdominal distension and a large palpable mass; the first infant also had intermittent non-bilious vomiting and a coexisting umbilical hernia, while the second child had a longer history of bilious vomiting and gradual abdominal enlargement over several years. These findings mirror previous reports in which giant mesenteric cysts produced symptoms predominantly through mass effect and compression of adjacent bowel rather than through acute complications such as volvulus or rupture.^6,7,9

Radiological imaging remains essential for the preoperative assessment of mesenteric cysts. Ultrasonography is generally the first-line modality, as it is widely available, inexpensive, and reliably differentiates cystic from solid abdominal masses, while also providing information on septations, internal echogenicity, and the relationship of the cyst to surrounding structures.^2,10 Contrast-enhanced CT, and occasionally MRI, are valuable for delineating the full extent of giant cysts and their relationship to the bowel, mesenteric vessels, and adjacent organs, which is important for operative planning, particularly when a cyst extends across multiple abdominal compartments as in our second patient.^2,10,12 In both of our cases, ultrasonography first raised the suspicion of a mesenteric cyst, and contrast-enhanced CT subsequently provided the anatomical detail required for surgical planning.

Complete surgical excision remains the treatment of choice for mesenteric cysts, regardless of symptom status, because of the risk of complications such as hemorrhage, infection, torsion, volvulus, bowel obstruction, and, rarely, malignant transformation if the cyst is left in situ.^2,3 The choice between cyst enucleation alone and excision combined with segmental bowel resection depends largely on the relationship of the cyst to the adjacent mesentery and bowel wall; resection becomes necessary when the cyst shares a common blood supply with the bowel or is so densely adherent that enucleation would compromise bowel viability.^2,3

Minimally invasive laparoscopic and even robotic-assisted approaches have been reported with good outcomes for pediatric mesenteric cysts, including some large lesions, although open laparotomy is often preferred for giant cysts because of the limited working space and the need for careful dissection from adjacent bowel.^3,5

In the first case, the giant cyst was densely associated with the jejunal mesentery, necessitating segmental jejunal resection with primary end-to-end anastomosis to achieve complete excision, together with repair of the coexisting umbilical hernia. In the second case, the cyst could be completely excised from beneath the stomach without bowel resection. Histopathological examination in both patients confirmed a benign mesenteric cyst, consistent with the predominance of lymphatic malformations (cystic lymphangiomas) reported in pediatric series, and with the literature indicating that malignant transformation of mesenteric cysts is exceptionally rare and occurs almost exclusively in adults.^4,5

The prognosis after complete surgical excision of a mesenteric cyst is generally excellent, with low rates of recurrence and complications reported in recent pediatric series, even for giant or complex cysts requiring bowel resection.^3,4 Recurrence is most often related to incomplete excision, marsupialization, or simple drainage rather than to complete resection.^3,4 Both of our patients had an uneventful postoperative course and remained asymptomatic, with no evidence of recurrence at six months of follow-up, supporting complete surgical excision as definitive treatment for this rare condition.

Our cases highlight the importance of considering mesenteric cysts in the differential diagnosis of pediatric abdominal masses and abdominal distension. Early recognition, appropriate imaging evaluation, and complete surgical excision are essential to prevent complications and achieve optimal clinical outcomes.

Conclusion

Mesenteric cysts are rare benign intra-abdominal lesions that should be considered in the differential diagnosis of abdominal masses and distension in pediatric patients. Early diagnosis through appropriate imaging modalities, particularly ultrasonography, is essential for determining the size, location, and extent of the lesion and for guiding surgical planning. Complete surgical excision remains the treatment of choice and may require resection of the adjacent bowel segment when the cyst is closely associated with the intestinal wall or mesenteric vasculature. Timely surgical management is associated with excellent outcomes, low recurrence rates, and minimal postoperative complications. Our cases highlight the importance of early recognition and definitive surgical treatment in achieving favorable clinical outcomes.

Funding Statement

We declare that we have not received any financial support.

Ethical Approval

Based on the regulations of the review board of the Mogadishu Somali Turkish Recep Tayyip Erdoğan Research and Training Hospital, institutional review board approval is not required for case reports.

Consent for Publication

Written informed consent was obtained from both patient’s parents for publication of the case details and accompanying images. A copy of the signed consent form has been provided to the journal and is available for review by the Editor-in-Chief upon request.

Disclosure

No conflicts of interest in this work.