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444 E. G. Wong and J. V. Sakran
Suggested Reading
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Smith MTD, Clarke DL. Defining an intra-operative blunt mesenteric injury grading system
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Mesenteric Cysts
Paul T. Hernandez and Nicole M. Saur
Cystic Tumors of the Mesentery
Cystic tumors of the mesentery are a diverse group of rare tumors that occur across
all ages and genders. Given the rarity of these tumors, with the cumulative incidence of approximately 1 in 100,000 to 1 in 250,000 hospitalized patients, they are
often lumped under the catchall term “mesenteric cysts”. Though frequently treated
as a single entity, mesenteric cysts can be divided into six distinct groups based on
their histopathologic features or cell-type of origin, with each group of tumors
having a distinct epidemiology and biologic behavior. These groups include:
(1) cysts of lymphatic origin including lymphangioma, (2) cysts of mesothelial
origin including simple mesothelial cysts and multi cystic mesothelioma, (3) enteric
duplication cysts, (4) urogenital cysts, (5) cysts derived from germ cells including
mature cystic teratoma, and (6) post-traumatic/post-infectious pseudocysts. The
management of these lesions varies from observation to emergent surgery
depending on patient factors and the presence of and severity of symptoms.
46
Description of Condition
Mesenteric Lymphangioma
Lymphangioma are benign, congenital tumors characterized by the proliferation of
thin-walled lymphatic channels. It is hypothesized that lymphangiomas are formed
when primitive lymph vessels fail to connect with the remainder of the lympho-
P. T. Hernandez N. M. Saur (&)
Department of Surgery, Division of Colon and Rectal Surgery, University of Pennsylvania,
Perelman School of Medicine, 800 Walnut St. 20th Floor, Philadelphia, PA 19106, USA
e-mail: nicole.saur@uphs.upenn.edu
© Springer Nature Switzerland AG 2021
E. D. Ehrenpreis et al. (eds.), The Mesenteric Organ in Health and Disease,
https://doi.org/10.1007/978-3-030-71963-0_46
445
446 P. T. Hernandez and N. M. Saur
Fig. 46.1 Left: Numerous dilated lymphatic spaces, sometimes filled with lymph (EE 5X). Inset:
focally lymphatic spaces are covered by plump endothelial cells (EE 20X). Right: Thin walled,
multiseptated cyst filled with serous fluid. Aprea, Giovanni, Francesco Guida, Alfonso Canfora,
Antonio Ferronetti, Antonio Giugliano, Melania Ciciriello, Antonio Savanelli, and Bruno Amato.
“Mesenteric Cystic Lymphangioma in Adult: A Case Series and Review of the Literature.” BMC
Surgery 13, no. Suppl 1 (2013): A4. https://doi.org/10.1186/1471-2482-13-S1-A4. Reused with
permission © Springer Nature
vascular system during embryonic development. Grossly, these tumors appear as
thin-walled, multiseptated cysts that contain serous to chylous lymphatic fluid. On
pathology, these tumors are characterized by dilated lymphatic channels and large,
irregular lymphatic spaces lined by bland epithelial cells and smooth muscle.
Among the cystic tumors of the mesentery, lymphangiomas are the most common.
The most common sites for lymphangioma are the head, neck, and axilla;
approximately 9% of lymphangioma occur in the peritoneal cavity. Less than 1%
occur in the mesentery, with the most common site being the mesentery of the small
bowel. Mesenteric lymphangioma may also involve the wall of the adjacent bowel.
Almost 90% of intraabdominal lymphangioma are diagnosed by 2 years of age.
Malignant transformation of mesenteric lymphangioma is exceedingly rare, but has
been reported in the literature (Fig. 46.1).
Simple Mesothelial Cysts
It is hypothesized that simple mesothelial cysts form when the mesenteric leaves
fail to fuse during development. The resulting tumor is a thin-walled unilocular cyst
filled with serous fluid. On histology, these tumors h ave a fibrous wall that is devoid
of a defined muscular layer and are lined by an attenuated layer of mesothelium.
While generally considered benign, there have been isolated reports of malignant
transformation in the literature. Mesothelial cysts have been described in all portions of the mesentery from the ligament of Treitz to the mesorectum, but the most
commonly reported site is the ileal mesentery (Fig. 46.2).
46 Mesenteric Cysts 447
Fig. 46.2 Large thin-walled, unilocular cyst. Ousadden, Abdelmalek, Hicham Elbouhaddouti,
Karim Hassani Ibnmajdoub, Taoufiq Harmouch, Khalid Mazaz, and Khalid AitTaleb. “A Giant
Peritoneal Simple Mesothelial Cyst: A Case Report.” Journal of Medical Case Reports 5, no.
1 (December 2011). https://doi.org/10.1186/1752-1947-5-361
Multicystic Mesothelioma
Multicystic mesothelioma of the peritoneum is a rare tumor that arises from the
epithelial and mesenchymal elements of mesothelial tissue. In contrast to malignant
peritoneal mesothelioma, which is an aggressive and universally fatal disease,
multicystic mesothelioma is considered benign and has an extremely low potential
for malignant transformation. The incidence of the disease is *0.15 per 100,000
cases annually. Unlike malignant mesothelioma which typically occurs in men and
has a strong association with asbestos exposure, multicystic mesothelioma has been
reported in both sexes but typically affects the pelvic peritoneum of premenopausal
women though involvement of the small bowel mesentery is possi ble. Involvement
of the mesocolon of the sigmoid and transverse colon are also well described.
Grossly, the tumor is characterized by its multicystic “bunch of grapes” appearance
with individual cysts that range in size from several millimeters to 20 cm and are
filled with thin serous or gelatinous fluid. Microscopically, the cysts are lined by a
thin layer of flattened cuboidal or hobnail mesothelial cells and are separated by
fibrous tissue. Multicystic mesothelioma has an association with previous surgery,
endometriosis and familial Mediterranean fever. Given the significant differences in
the biological and clinical behavior between malignant peritoneal mesothelioma
and multicystic mesothelioma, some hypothesize that multicystic mesothelioma is a
hyperplastic rather than neoplastic process. Nonetheless, multicystic mesothelioma
has a high propensity for local recurrence with 25–50% recurrence rates after
surgical resection, and while very rare, malignant transformation has been
described.
448 P. T. Hernandez and N. M. Saur
Enteric Duplication Cysts
These developmental anomalies are cystic or tubular bowel-like structures situated
adjacent to the luminal GI tract. Like the adjacent bowel, duplication cysts are lined
by intestinal epithelium and have a well-defined outer layer of smooth muscle
complete with myenteric neural elements. Heterotopic gastric mucosa can also be
present in up to 50% of cases, especially in duplications of the ileum and the colon.
There are two morphologic types of enteric duplication cysts, cystic-type and
tubular-type. Cystic-type duplications, which make up the majority, are spherical in
shape and have no communication with the lumen of the adjacent bowel, though
they typically share a common wall and a blood supply with the adjacent segment
of intestine. Tubular duplications, which account for approximately 20% of the
cases, are often long and tubular and do typically communicate with the adjacent
bowel. While duplication cysts can occur anywhere along the GI tract from the
mouth to the anus, they are most frequently encountered in the jejunum and ileum
on the mesenteric side of the lumen.
There have been many proposed embryologic mechanisms for the formation of
enteric duplication cysts, and no mechanism has gained universal acceptance. The
split notochord hypothesis, which proposes an abnormal separation of the notochord from the gut endoderm resulting in enteric duplication or diverticula, has
gained the most favor as this hypothesis also explains the 15% association of
developmental vertebral abnormalities with enteric duplications. As they are congenital tumors, the majority become symptomatic or are discovered incidentally
before 2 years of age.
Malignancy is rare, but can arise in enteric duplications. They occur most
commonly in colonic duplications as up to 67% of malignancies diagnosed in
duplication cysts occur in this location. Malignant transformation can also occur in
small bowel duplications, and is more common among duplications with heterotopic gastric mucosa.
Urogenital Cysts of the Mesentery
Urogenital mesenteric cysts are rare congenital tumors thought to arise from vestigial remnants of the embryonic urogenital apparatus. On histology, these cysts are
lined by cuboidal to columnar epithelium. They may also demonstrate some elements of distinct pronephric, mesonephric, metanephric, or Mullerian differentiation including various primitive renal elements and fallopian tube-like ciliated
epithelium. Grossly, the cysts are typically thin-walled and contain a mix of serous
fluid and adipose tissue (Fig. 46.3).
46 Mesenteric Cysts 449
Fig. 46.3 Cyst with fibromuscular wall covered by ciliated epithelium, of Mullerian type.
Mokhtari M, Kumar PV. Cytologic findings of urogenital mesenteric cyst. Arch Iran Med. 2013;
16(7):436–438. © 2021 The Author(s). This work is licensed under a Creative Commons
Attribution 4.0 License
Mature Cystic Teratoma
Mature cystic teratomas, otherwise known as dermoid cysts, are germ cell tumors that
arise from totipotent primordial germ cells. These tumors have a cyst wall lined by
flattened cuboidal epithelium and contain a mix of tissues derived from all three germ
cell layers including tissue of ectodermal (i.e. skin, hair follicles, sebaceous glands,
teeth), mesodermal (i.e. muscle, urinary), and endoderm origin (i.e. lung, gastrointestinal) as well as liquid sebaceous material. Macroscopically, these tumors are thick walled,
septated cysts that contain a thick, fatty, gelatinous material as well as teeth and hair.
Teratomas can occur anywhere along the pathway of germ cell migration, most
commonly in the midline, from the cranium to the sacrococcygeal region. The most
common location is the sacrococcygeal region and the gonads, but there are numerous
reports of these tumors occurring in the small bowel mesentery, making mature cystic
teratomas an important entity in the differential diagnosis of a mesenteric cyst.
While the vast majority of these tumors occur in adult females, isolated cases
have been reported in male patients. Mature cystic teratomas are considered benign,
but malignant transformation occurs in 0.2 to 2% of these tumors with increased
risk of malignancy in patients 45 years and older and those with rapidly growing
tumors or tumors greater than 10 cm in diameter (Fig. 46.4).
Mesenteric Pseudocyst
Similar to the more common pancreatic pseudocysts, mesenteric pseudocysts are
fluid collections encased fibrous tissue without an epit helial lining. Mesenteric
pseudocysts are not associated with pancreatitis and are thought to occur secondary
450 P. T. Hernandez and N. M. Saur
Fig. 46.4 Teratoma within the mesentery of the ileum. Pandya Jayshri et al. Mature mesenteric
teratoma in an adult male. Panacea Journal of Medical Science 2015; 5(3):161–163. Copyright
© 2015 by author(s) and Panacea J Med Sci. This is an Open Access article distributed under the
terms of the Creative Commons Attribution 4.0 International License (creativecommons.org)
to trauma, infections, or prior surgery when a hematoma or abscess is formed in the
mesentery and not completely absorbed. As a result, the persistent cyst is often
filled with hemorrhagic contents and cellular debris.
Mesenteric pseudocysts occur most commonly in patients in their 40 s and are
reported more commonly in females than in males (Fig. 46.5a and b).
Presentation and Diagnosis
Cystic tumors of the mesentery have a wide spectrum of presentations. Approximately 40% of mesenteric cysts are discovered incidentally on physical exam, on
imaging, or during abdominal surgery for other indications. Of the remaining 60%
of patients, the majority present with chronic, non-specific symptoms including
mild abdominal pain, abdominal bloating, or abdominal distension. Only 5 to 10%
of patients will ultimately present with acute complications of their cysts.
Diagnostic Studies in Uncomplicated Mesenteric Cysts
The majority of cystic tumors of the mesentery are discovered incidentally on
abdominal imaging, physical exam, or in the setting on non-specific abdominal
symptoms. Ultrasound (US) and commuted tomography (CT) are the most commonly utilized imaging modalities in the diagnosis of mesenteric cysts. While less
commonly employed, magnetic resonance (MR) imaging can sometimes more
accurately describe the relation between the mass and the adjacent organs and soft
tissues or provide additional information regarding the nature of the cyst contents.
46 Mesenteric Cysts 451
Fig. 46.5 a and
b Histopathology of the
pseudocyst wall showing
dense fibrous tissue with no
epithelial lining. Geng,
Jiun-Hung, Chun-Hsiung
Huang, Wen-Jeng Wu,
Shu-Pin Huang, and Yi-Ting
Chen. “Huge Retroperitoneal
Nonpancreatic Pseudocyst.”
Urological Science 23, no.
2 (June 2012): 61–63. https://
doi.org/10.1016/j.urols.2012.
03.002. Reused with
permission © Elsevier
Physical Exam
When discovered on physical exam, a mesenteric cyst may demonstrate a triad of
findings first described by Paul Jules Tillaux in the late nineteenth century. Tillaux’s
triad includes (1) a fluctuant abdominal mass near the umbilicus that (2) is mobile
only from the patient’s right to left or left to right and (3) is dull to percussion but
encircled by zone of tympani representing the surrounding bowel.
Imaging
Each imaging modality for the evaluation of mesenteric cyst has its own benefits
and limitations. US has the benefits of being both widely available and cost
effective. Unlike CT, US does not emit ionizing radiation making it the study of
452 P. T. Hernandez and N. M. Saur
choice in children. US, however, is operator dependent and does not demonstrate
the relationship of the mesenteric cyst to adjacent organs as well as CT and MR.
While all varieties of mesenteric cysts share the common characteristics of being
well-defined, hypoechoic/hypoattenuating masses, subtle differences in the radiologic appearances of the different types of mesenteric cysts can facilitate the making
a pre-operative diagnosis.
Lymphangioma
By US, lymphangiomas appear as thin-walled, cystic, multiseptated/lobulated
mases that may contain internal echoes, sedimentation or fluid–fluid levels caused
by cellular debris.
On CT, mesenteric lymphangioma appear as cystic masses with Hounsfield units
(HU) ranging from water attenuation for cysts with predominantly serous contents
to fat attenuation for cysts with predominantly chylous contents. When performed
with intravenous contrast, the cyst wall may show enhancement. The fine septa,
readily appreciable by ultrasound, are usually less apparent on CT though there are
occasionally calcifications that form along the septa and revealing their presence.
For mesenteric lymphangioma, MR can provide additional information that can
further clarify the diagnosis. These tumors are hyperintense on T2-weighted images, and their internal septae are much more apparent when compa red to CT.
Typically, the cyst contents demonstrate high signal intensity on T1-weighted
images, and a comparison of in-phase and opposed-phase T1-weighted images can
demonstrate the fact that these tumors contain both a significant amount of fat and
water as expected in lymphatic fluid. This technique allows lymphatic cysts to be
differentiated from cystic masses that contain purely serous fluid and those that are
purely fat containing.
Mesothelial Cysts
By US, mesothelial cysts are similarly thin-walled and anechoic, but they typically
lack the septations and internal debris seen in lymphangiomas. These cysts often
demonstrate strong posterior acoustic enhancement. CT and MR demonstrate a
cystic mesenteric mass without a discernable wall or septations. The cyst fl uid is
also different from that of lymphangiomas in that it has Hounsfield units by CT
closer to water than fat, and the fluid has low signal intensity on T1-weighted
images as compared to the high signal intensity in lymphangiomas.
Multicystic Mesothelioma
With a similar appearance to lymphangioma, multicystic mesothelioma appear as a
hypoechoic, multiloculated mass on US. CT commonly demonstrates a cysti c mass
with homogeneous fluid attenuation and no calcifications. As with lymphangioma,
CT may or may not demonstrate the multilocular nature of the mass. On MR, these
46 Mesenteric Cysts 453
cystic lesions show low signa l intensity on T1-weighted images and high signal
intensity on T2-weighted images without any solid components or enhancement.
Enteric Duplication Cysts
Ultrasonography of enteric duplication cysts classically demonstrates a
double-layered wall with an inner layer of hyperechoic mucosa and an outer layer
of hypoechoic muscle often referred to as the “gut signature”. When present in a
cyst the “gut signature” has a high speci ficity for an enteric duplication cyst, but in
many cases inflammation may obscure this classic sign (Fig. 46.6).
By CT, enteric duplications are flat, spherical or tubular tumors situated adjacent
to a loop of bowel. They can displace but show no evidence of infiltrating other
organs. As with the adjacent bowel, the wall of duplications generally demonstrates
mucosal enhancement with intravenous contrast. If distended with fluid at the time
of CT, cyst conten ts have Hounsfield units in the 0–20 range. MR imaging similarly
demonstrates a well-circumscribed, homogeneous, hypointense mass on
T1-weighted images. On T2-weighted images of the distended cyst contents are
hyperintense, though there may be variability in the signal due to associated
hemorrhage or mucous secretion. As with CT, gadolinium-enhanced MRI shows
enhancement of the cyst wall.
Fig. 46.6 Portions of the cyst wall show the characteristic double-layered appearance with
echogenic mucosa internally (arrows) and hypoechoic muscle externally. Di Serafino, Marco,
Carmela Mercogliano, and Gianfranco Vallone. “Ultrasound Evaluation of the Enteric Duplication
Cyst: The Gut Signature.” Journal of Ultrasound 19, no. 2 (June 2016): 131–33. https://doi.org/10.
1007/s40477-015-0188-8. Reused with permission © Springer Nature