Mesenteric cyst: A rare cause of lower abdominal pain

Marjun P. Duldulao, BS

Medical Student III

Arumugam Thiruchitrambalam, MD

Fellow in Minimally Invasive Surgery

Ashutosh Kaul, MD, FRCS

Director

Minimally Invasive and Robotic Surgery Associate Professor of Surgery New York Medical College Valhalla, NY

ABSTRACT Introduction: Mesenteric cysts are rare and may occur in patients of any age. They are often asymptomatic and found incidentally, although patients may present with lower abdominal pain and symptoms that are frequently associated with other abdominal conditions, such as appendicitis and diverticulitis. Mesenteric cysts generally arise within the mesentery of the small bowel in the ileum.

Results and discussion: A 38-year-old woman presented to the emergency department after experiencing 3 days of persistent abdominal pain, nausea, and constipation. A computed tomography (CT) scan revealed a large abdominal cyst, which was excised during laparotomy and pathologically identified as an inflammatory pseudocyst of the mesentery. The authors discuss this case and review various theories regarding the etiology of mesenteric cysts, along with their presentation, diagnosis, and treatment.

Conclusion: The exact etiology of mesenteric cysts is unknown. CT scanning and ultrasonography are instrumental in diagnosing mesenteric cysts and ruling out other conditions in patients who present with symptoms of abdominal disease. Surgical removal is the only treatment for these lesions. Bowel resection may be necessary in cases where cysts are close to bowel structures or involve blood vessels that supply the bowel. Once removed, mesenteric cysts rarely recur, and patients have an excellent prognosis.

Mesenteric cysts are a rare cause of abdominal pain. They are identified in approximately 1 of every 100,000 adult hospital admissions.¹-³ The etiology of mesenteric cysts has yet to be determined, but failure of the lymph nodes to communicate with the lymphatic or venous systems or blockage of the lymphatics as a result of trauma, infection, and neoplasms are said to be contributing factors.^1,4

Mesenteric cysts are typically discovered incidentally while patients are undergoing work-up or receiving treatment for other conditions, such as appendicitis, small bowel obstruction, or diverticulitis. Clinically, patients with these cysts present with abdominal pain, distention, vomiting, and nausea, which is the common symptomology for abdominal disease. Performing a thorough physical examination and conducting ultrasonography and computed tomography (CT) evaluations are key in diagnosing mesenteric cysts.

We report the case of a woman who presented with right lower quadrant abdominal pain, nausea, constipation, and abdominal distention. Laboratory tests demonstrated an elevated white blood cell count (WBC), and CT scanning showed a large abdominal cyst. Laparotomy was performed, and the excised lesion was subsequently identified as a mesenteric cyst of the nonpancreatic pseudocyst variety.

CASE REPORT

A 38-year-old woman came to the emergency department after experiencing 3 days of diffuse abdominal pain, nausea, and constipation. Nothing seemed to alleviate or exacerbate the pain, which was constant. It was located primarily on the right side of her abdomen and did not radiate to her back or shoulders. She had no vomiting or diarrhea, and her last bowel movement occurred 3 days earlier and was nonbloody. She reported no recent fevers, change in weight, chest pain, shortness of breath, coughing, dysuria, or vaginal discharge.

The patient's medical history was negative for diabetes, hypertension, bleeding disorders, peptic ulcer disease, and cholelithiasis. Her pregnancy history indicated that she was gravida 2, para 2, and both deliveries were via Cesarean section, with the last one taking place 12 months prior to her current presentation. She had no other surgical history. Following delivery, the patient suffered from postpartum depression and, at presentation, was using the medications alprazolam (Xanax, Niravam), paroxetine (Seroxat, Paxil), and olanzapine (Zyprexa). She was also taking docusate (Colace, Dialose, DSS, Surfak) to treat ongoing constipation.

On physical examination, the patient was afebrile and suffering mild pain and distress. Her vital signs were stable, and respiratory and cardiac examinations were normal. Her abdomen was slightly distended and tender in all four quadrants, with maximum tenderness elicited in the right lower quadrant on palpation. Bowel sounds were decreased, and no masses were palpable. The patient had voluntary guarding but no rebound tenderness or costovertebral-angle tenderness. A rectal examination found trace blood and stool in the rectal vault, and a pelvic examination revealed no vaginal discharge or cervical motion tenderness.

Laboratory tests found a WBC of 19.8 x10⁹/L (normal, 4.5-11.0 x10⁹/L), hemoglobin count of 114 g/L (normal, 120-150 g/L), hematocrit of 0.335 (normal, 0.350-0.450), and platelet count of 289 x10⁹/L (normal, 150-450 x10⁹/L). Her blood differential showed 0.76 neutrophils (normal, 0.56), 0.11 lymphocytes (normal, 0.34), 0.12 monocytes (normal, 0.04), 0.004 eosinophils (normal, 0.027), and 0.002 basophils (normal, 0.003). Her liver function tests, basic metabolic panel, amylase and lipase levels, and urinalysis were within normal limits. A beta human chorionic gonadotropin test was negative.

6.7

A chest radiograph showed no infiltrates in the lower lung fields. The patient underwent intravenous (IV) and oral contrast-enhanced CT scans of the abdomen and pelvis, which demonstrated a large mass in the right side of the abdomen. The mass measured 10.3 x cm in maximal axial dimension and 9.0 cm in cephalocaudad extent (Figure 1). It was irregular and somewhat lobulated in contour and primarily consisted of water attenuation but with an enhancing peripheral rim. Trace fluid was seen in the subhepatic space. The left lateral aspect of the mass abutted the patient's small bowel, which was not distended. It was not clear whether the mass originated from the bowel or from the mesentery. Several sub-centimeter abdominal and retroperitoneal nodes were also observed. The remaining abdominal viscera showed no evidence of cysts, masses, or inflammation.

The patient was resuscitated, and she underwent diagnostic laparoscopy with lysis of the adhesions. The cyst was large and too difficult to manipulate, so a midline incision was made and the laparoscopy was converted to an open procedure. A large, yellow, lobulated, smooth cyst firmly attached to the mesentery of the small bowel was identified. It did not adhere to the small bowel, stomach, or colon. Using blunt and sharp dissection, the cyst was mobilized from the small bowel mesenteric vessels to which it was attached, with care taken to preserve blood supply to the patient's bowel. The cyst was opened outside the patient and found to be filled with sero-purulent brownish fluid, which was sent for Gram stain and culture, while the cyst was sent for histological evaluation. The bowel was inspected for strictures, adhesions, and ischemia. The abdomen was closed after no abnormalities were discovered. The patient's recovery was uneventful, and she was discharged from the hospital on postoperative day 4.

Pathologic examination of the mass found it to be cystic, walled by fibro-fatty and granulated tissue, and with focal sclerosis (Figure 2). Inflammatory pseudocyst of the mesentery was diagnosed. The external surface of the cyst was smooth with focal tan exudates, and it was filled with cloudy gray-brown fluid. Cut section revealed a cystic space filled with fibrinous exudates that had varying wall-thickness. Focal areas of hemorrhage were also noted. The internal lining of the mass was irregular, and there were multiple discolored dark brown areas. Microscopic inspection showed no epithelial lining (Figure 3). The cavity contained mixed inflammatory cells admixed with abundant fibrin material. No granulomas were noted. The infectious disease report showed that there were no acid-fast staining organisms. Intraoperative cultures of pelvic and cystic fluid were negative for colonies after 7 days.

DISCUSSION

Mesenteric cysts are rare and are found in approximately 1 of every 100,000 adult patients admitted to the hospital.¹³ They are often classified as omental cysts because of the similar etiologies and histologic features of these lesions. Although one third of all reported cases of mesenteric and omental cysts occur in children under age 15, the cysts seem to have no age predilection and cases have been reported in both newborns and patients in their seventies.^1,5 Mesenteric cysts occur approximately 4.5 times more frequently than omental cysts.¹

Etiology and location

Although the exact etiology of mesenteric cysts is unknown, several theories have been proposed. One of the leading theories suggests that they are benign proliferations of ectopic lymphatics that fail to communicate with the remaining lymphatic system.^1,6 Other theories include a failure of the embryonic lymph channels to join the venous system, trauma, neoplasia, and lymph node degeneration.⁵ It is possible that our patient's previous Cesarean sections contributed to the development of her mesenteric cyst.

Mesenteric cysts can be found in several locations in the body; these range from the mesentery of the duodenum to the sigmoid colon and even within the retroperitoneum. They are most commonly observed within the mesentery of the small bowel in the ileum.^1,3,5,7 In a series of 162 patients, Kurtz reported that 60% of mesenteric cysts occurred in the small bowel, 24% in the large bowel mesentery, and 14.5% in the base of the mesentery in the retroperitoneum.³

Presentation and classification

Mesenteric cysts vary in their clinical presentation. Some are discovered incidentally, whereas others cause abdominal symptoms. There are no specific symptoms indicative of mesenteric cysts, which is the reason these lesions are often confused with other abdominal diseases at presentation, such as appendicitis, ovarian torsion, diverticulitis, and small bowel obstruction.

Our patient experienced persistent abdominal pain, and her recent symptoms and clinical examination suggested appendicitis or small bowel obstruction. Some patients present with one or all of the following: abdominal distention, diffuse tenderness, vomiting, nausea, and a palpable mass. On physical examination, it may be difficult to palpate the cyst due to guarding and a tense abdominal wall. Secondary complications associated with mesenteric cysts include volvulus, spillage of infective fluid, herniation of bowel into an abdominal defect, and obstruction.^7,8

Mesenteric cysts commonly occur as single lesions, but multiple lesions have been reported. They can be unilocular or multilocular and may contain serous, chylous, hemorrhagic, or infective fluid. Cyst contents are sometimes related to their etiologic derivation. Cysts that develop after occult trauma may contain hemorrhagic content; chylous fluid may be found in jejunal cysts and in cysts that are intimately involved in the lymphatic pathway; and serous fluid is typically encountered in cysts of the ileum and colonic mesentery.^4,6,9

Practice

Point

Some mesenteric cysts are discovered incidentally, whereas others cause abdominal symptoms.

Based on their histology, mesenteric cysts can be further classified as simple mesenteric cysts, lymphangiomas, nonpancreatic pseudocysts, enteric duplication cysts, enteric cysts, and mesothelial cysts. Each type is distinguished by its unique endothelial lining and contents. Lymphangiomas are more common among children, and the remaining classes are more frequently observed in adults.^1,3-5

Diagnosis and treatment

Accurately diagnosing a mesenteric cyst depends on performing a thorough physical examination and conducting appropriate radiological studies.^4,5,8 Abdominal radiographs are nonspecific but may show displacement of bowel to one side or obstruction resulting from an enlarged cyst. Ultrasonography can characterize an abdominal mass as cystic or solid and is the imaging modality of choice for suspected mesenteric cysts. Ultrasonography can depict fluid-filled cystic structures, the presence of septations, and internal echoes of debris, hemorrhage, or infection. CT scanning can help establish the point of origin and allow the clinician to rule out other abdominal pathologies, such as appendicitis, bowel obstruction, inflammation, free-fluid, pneumoperitoneum, and perforation. Complete surgical excision is the best way to manage mesenteric cysts. Some patients may require bowel resection to achieve complete removal of the cyst if it is closely associated with bowel structures or involves blood vessels that supply the bowel. The need for bowel resection is primarily associated with lymphangiomas.⁴ Postoperatively, patients rarely experience any adverse events. Mesenteric cysts have a reportedly low recurrence rate, which ranges from 0% to 13.6%.⁶

CONCLUSION

Mesenteric cysts are rare and do not always produce symptoms. Asymptomatic cysts are discovered incidentally. Patients who are symptomatic generally present with abdominal distress and any combination of distention, pain, a palpable mass, nausea, and vomiting. Cysts are sometimes misdiagnosed as common abdominal conditions. Mesenteric cysts may result from lymphatic malformations, occult trauma, or infection. Ultrasonography and CT scanning are the most useful imaging modalities for diagnosing mesenteric cysts preoperatively. Mesenteric cysts are usually found within the ileal mesentery and are treated successfully with complete surgical excision. Following surgery, patient prognosis is excellent and recurrence is low.

Disclosure

The authors have no relationship with any commercial entity that might represent a conflict of interest with the content of this article and attest that the data meet the requirements for informed consent and for the Institutional Review Boards.

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