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474 S. H. Emile
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Mesenteric Neoplasms
Rishabh Sehgal, J. Calvin Coffey, and Deborah S. Keller
Introduction
Traditional teaching has perceived the mesentery as a fragmented structure with
complex relationships to surrounding intraabdominal structures. This concept has
been indoctrinated into mainstream surgical and anatomical literature for over a
century. Recent research and formal appraisal of the mesentery has defined it as a
unique organ, continuous from the duodeno-jejunal flexure to the mesorectum.
Histological and electron-microscopic studies have expanded on the details of the
mesenteric organ, demonstrating it consists of a surface mesothelium and underlying connective tissue throughout. Fibrous septae divide adipocyte lobules within
the body of the mesocolon. Where in contact with the retroperitoneum, the
mesentery is the mesocolon, and two mesothelial layers are separated by a distinct
layer of connective tissue—Toldt’s fascia—separates both. Lymphatic channels are
evident both in mesenteric connective tissue and Toldt’s fascia. The new model of
the mesentery organ provides us with an opportunity to understand disease states
that involve the mesentery.
The rich network of lymphatics and close relationship of the mesentery to other
intra-abdominal structure, mean the mesentery is prone to a myriad of disease
states. When pathological proces s originate from the mesentery itself, and spread to
48
R. Sehgal
Department of Colorectal Surgery, University Hospital Limerick, Limerick, Ireland
J. C. Coffey
School of Medicine and Department of Surgery, University of Limerick Hospital Group,
Limerick, Ireland
D. S. Keller (&)
Division of Colon and Rectal Surgery, NewYork-Presbyterian, Columbia University Medical
Center, Herbert Irving Pavilion, 8th Floor, 161 Fort Washington Avenue, New York, NY
10032, USA
e-mail: debby_keller@hotmail.com
© 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_48
475
476 R. Sehgal et al.
involve adjacent structures, this is known as a primary mesenteropathy. In contrast
secondary mesenteropathies are diseases where the primary abnormality originates
outside the mesentery and indirectly involves the mesentery. Neoplasms of the
mesentery are rare and usually diagnosed incidentally on radiological imaging.
They encompass a heterogenous group of lesions ranging from benign cysts to
aggressive malignancies. They can arise from distinct cellular components of the
mesenteric organ, including the peritoneal surface, connective tissue, adipocytes,
lymph nodes, and blood vessels, with a wide spectrum of surgical management
options. In this chapter, we describe the major types of mesenteric neoplasms,
indications and contraindi cations for surgery, and the surgical management for
mesenteric neoplasms.
Description of Mesenteric Neoplasms
Tumors of the mesentery are rare neoplasms first described in the early twentieth
century. Since the initial description of mesenteric tumors, experience has accumulated in treating these lesions, and a more complete picture has emerged of
diseases that manifest as mesenteric masses (e.g. lymphoma, desmoid tumors,
Castleman’s disease). Although uncommon, they are encountered in all age groups,
so an increased awareness of these tumors is important in the differential diagnosis of
abdominal masses and to aid in recognition and proper management (Table 48.1).
Anatomically, the mesentery spans the entire length of the intestine and consists
of fibrofatty, fanlike structure containing arterial, venous, lymphatic, and neural
structures in contiguity. The mesentery of the small bowel mese ntery and portions
of the colon mesentery are mobile, while the ascending and descending colon
mesenteries are normally fixed against the retroperitoneum. The greater and lesser
omentum are also included in the classification of mesentery, and tumors of these
structures are generally deemed as mesenteric. According to this model, the vast
majority of mesenteric tumors originate in the small bowel or omentum.
Mesenteric tumors can be either cystic or solid. Cystic mesenteric masses affect
males and females equally with up to 60% involving the small bowel mesentery.
The estimated incidence of cystic mesenteric masses is approximately 1/100,000 in
Table 48.1 Mesentericopathies
Mesenteropathies
Primary Secondary Indeterminate
Crohn’s disease
Ischaemia
Mal or nonrotation
Volvulus
Internal herniation
Cysts
Schwannoma
Sclerosing mesenteritis
Epiploic appendagitis
Mesenteric adenitis
Appendicitis
Phlegmon
Metastatic disease
Desmoid tumor
Peritoneal carcinomatosis
Castleman’s disease
Lymphoma
Mesenteric cavitation syndrome
Adhesions
Diabetes mellitus
Atherosclerosis
Metabolic syndrome
Irritable bowel syndrome
48 Mesenteric Neoplasms 477
the adult population and 1/20,000 in the paediatric population. Up to 50% of cystic
mesenteric masses are cystic lymphangiomas. Lymphomas are the most common
solid primary mesenteric neoplasms. They affect 1 in 200,000–350,000 population,
with the B-cell subtype being most prevalent. Carcinoid tumors are slow growing
solid neuroendocrine neoplasms involving the gastrointestinal tract in 90% of cases.
Carcinoid tumors affecting the mesentery are mostly metastases. Mid-gut carcinoid
tumors involve the mesentery in 40 to 80% of reported cases. Intra-abdominal
desmoid tumors account for 8% of all desmoid tumors and usually involve the
small bowel mesentery. They are most commonly associated with Familial adenomatous polyposis (FAP) (in 70% of cases) in which their incidence ranges from
4–32%. The remaining types of mesenteric tumors are rare and sporadically
mentioned in literature. In this work, we will describe the most common types of
mesenteric neoplasms, with attention to their diagnostic algorithm, surgical options,
indications and contraindications for surgery, and common complications
encountered.
Lymphoma
Solid primary tumours of the mesentery are rare. Lymphoma is the most common
malignancy involving the mesentery. The incidence ranges between 1 in 200,000 to
1 in 350,000 population and the majority present after 60 years of age.
Non-Hodgkin’s lymphoma accounts for the majority of cases, with up to 70% being
large B-cell neoplastic subtype. The mesentery can be the first site in which lymphoma arises. This is referred to as primary lymphoma. Mesenteric lymphoma may
also involve the small bowel by means of direct extension or displacement due to
the mass effect. They most commonly present with abdominal pain and a palpable
abdominal mass. They can remain asymptomatic (even when the tumor burden is
high) or they can present with systemic symptoms such as fevers, rigors, weight
loss and night sweats. The latter symptoms are suggestive of advanced disease.
They rarely cause bowel obstruction, perforation or gastrointestinal bleeding.
Rarely, mesenteric lymphomas occur in association with immune thrombocytopenia and dermatitis herpetiformis.
Early in the course of the disease, involved mesenteric nodes are small, soft and
discrete. As disease progresses, enlarged nodes develop and often coalesce and tend
to form a conglomerate mass. Ultrasound scanning helps in confirming the clinical
suspicion and allows for localization and biopsy of lesions. Computed tomography
(CT) has a greater sensitivity and provides more detailed spatial resolution and
ideally should be performed after ultrasound to further stage the disease. Bulky
retroperitoneal adenopathy can often accompany primary mesenteric disease. CT
may demonstrate a large, lobulated and “cakelike” heterogeneous mass displacing
small bowel and containing areas of necrosis (low attenuation); or, ill-defined
infiltration of mesenteric fat. Pathognomonic features of mesenteric lymphoma (on
CT) include a round well-de fined homogenous mass encasing mesenteric vessels
478 R. Sehgal et al.
Fig. 48.1 CT image
mesenteric lymphoma.
Mesenteric lymphoma.
A large mass is seen
representing confluent
mesenteric adenopathy
(arrows) on both sides of the
mesenteric vessels. The
radiographic term for this
finding is the “sandwich
sign.”
giving rise to the so-called ‘sandwich or hamburger sign’. In this sign, mesenteric
adipose tissue and tubular vascular structures represent the “filling,” whilst the
homogeneous soft tissue masses represent the “sandwich bun” (Fig. 48.1).
Differential diagnosis includes carcinoma, sarcoma, carcinoid tumor, tuberculosis, Whipple disease, lymphadenopathy associated with acquired immunodeficiency syndrome, and inflammatory bowel disease. Although diagnosis of
mesenteric lymphoma can be obtained on radiologic findings alone, a tissue sample
is required for definitive diagnosis and treatment planning. Tissue may be obtained
laparoscopically or via open surgical means. Whilst the application of laparoscopic
methods to investigate and treat mesenteric masses represents an evolving area of
surgical care, the open approach may be safer, given proximity of masses to
mesenteric vessels. In patients whose disease must be distinguished only from that
requiring resection (i.e., lymphoma, mesenteric lipodystrophy), laparoscopy offers
considerable benefits as it avoids a full laparotomy incision.
Mesenteric lymphoma is treated by cytotoxic chemotherapy, with CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) regimen, plus the
monoclonal antibody rituximab the gold standard for the management of diffuse
large B cell lymphoma. Although some cases are diagnosed following resection of
an uncharacterized mesenteric mass, surgical treatment is best used as a diagnostic
tool when the diagnosis is probable but uncertain. Moreover, surgery is reserved for
the management of any complications that may arise due to the presence of the
lymphoma. Rare cases of surgical resection combined with chemotherapy in
patients with bulky mesenteric diffuse large B cell lymphoma have been reported.
48 Mesenteric Neoplasms 479
Desmoid Tumors
Desmoid tumors are clonal fibroblastic proliferations that arise from deep soft tissue
and are characterized by infiltrative growth and a tendency toward local recurrence
but an inability to metastasize. Desmoids can manifest as flat, fibrous, sheet-like
lesions or well defined and discrete masses (Fig. 48.2a–d). Desmoids account for
less than 3% of all soft-tissue sarcomas and 0.03% of all malignancies. The etiology
is unknown, however they are associated with familial adenomatous polyposis (FAP), especially in patients with a mutation at the 3′ end of the 1440 codon of
ab
cd
Fig. 48.2 Contrast-enhanced axial CT images from a patient with previously undiagnosed
Gardener syndrome. a: shows soft tissue attenuation in a stellate pattern within the mesenteric fat
that is intimately associated with small bowel loops (arrow). b: shows innumerable polyps
throughout the imaged colon. c: Desmoids are benign, inflammatory fibroblastic tumors. They
appear as well-circumscribed enhancing masses in the mesentery (arrows). d: Desmoids may also
present as masses of the anterior abdominal wall (asterix)
480 R. Sehgal et al.
the APC gene, and trauma, developing within 5 years after abdominal surgery.
Their development following trauma is thought to arise from prolonged acute and
chronic inflammatory. They have an equal gender distribution and affecting adults
in their 30 an d 40s. Desmoids affect the extremities, trunk, and abdominal cavity in
the majority of cases. Although only 5% of sporadic desmoids are intra-abdominal,
80% of patients with FAP-associated desmoids develop intra-abdominal disease
involving the small bowel mesentery. Patients with FAP and desmoid disease tend
to present with multiple but smaller lesions, whereas sporadic cases tend to present
with a solitary large lesion.
Mesenteric desmoids can be asymptomatic and diagnosed incidentally. They
may cause symptoms due to external pressure effect on the adjacent bowel, or by
impinging on the intestinal blood supply. Lesions that can extend retroperitoneally
leading to additional complications such as hydronephrosis. CT and MRI are the
main radiologic modalities used for inves tigating such mesenteric masses. Radiologically, mesenteric desmoids are represented by a soft-tissue mass, with displacement of bowel loops and surrounding vasculature, with or without intestinal
involvement and serosal changes. The soft-tissue component is a dominant feature
that can mimic other solid tumors, including gastrointestinal stromal tumor (GIST),
lymphoma, carcinoids, or fibrosarcomas.
In the case of mesenteric desmoid tumors, medical management with Sulindac,
Raloxifene, and chemotherapeutic agents such as Methotrexate, Vinorelbine, Doxil,
and Adriamycin are used to slow growth and ameliorate obstructive symptoms.
Radiotherapy is not generally recommended for retroperitoneal or intra-abdominal
desmoids, due to their proximity to key intra-abdominal structures. Surgery is
indicated for treatment of complications such as bowel obstruction, enterocutaneous
fistula, and ureteric obstruction. For resectable lesions, wide local excision with
macroscopic negative margins is the standard. The resultant mesenteric defect is
usually closed to avoid internal hernias. Smaller desmoids at a distance from major
vascular trunks, can be safely resected with minimal complications. Contraindications to surgery are location at the root of the small bowel mesentery or near other
critical structures; in these cases proximity to critical small bowel blood supply may
render the mass unresectable. Palli ative options include enteroenteric or enterocolic
bypass. These can be performed either laparoscopically or via an open approach.
Small bowel and multi-visceral transplant have been described as surgical options.
Although Chatzipetrou et al. reported more than 80% enteral independence and one
recurrence in patients who underwent intestinal transplantation for desmoid tumors
other transplant groups have reported very poor outcomes for transplantation with
respect to complicated intra-abdominal desmoids.
48 Mesenteric Neoplasms 481
Mesenteric Gastrointestinal Stromal Tumors
Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the gastrointestinal tract arising from the ‘pacemaker cells’ that regulate peristalsis, i.e. the
interstitial cells of Cajal. GISTs account for less than 5% of all gastrointestinal
malignancies and most commonly affect adults in between ages 40 and 70 years.
Mazur and Clark were first to describe GIST as gastrointestinal tract nonepithelial
neoplasm that did not possess the ultrastructural characteristics of smooth muscle
cells, and immunohistochemical features o f Schwann cells. Immunohistoch emical
staining demonstrates expression of CD-117 (95%) and CD-34 (70%) protein and
mutations of C-kit and PDGFRA genes are frequent.
Primary GIST mostly occur as solitary lesions involving the stomach (60–70%)
followed by small bowel (20–25%). Less frequent sites include the colon, rectum,
esophagus and appendix (Fig. 48.3a and b). There are also sporadic reports of GIST
arising in the omentum, mesentery and retroperitoneum. They can be asymptomatic, present as a palpable abdominal mass or as acute abdomen due to rupture.
Ultrasound and CT are the main diagnostic modalities used to asses stage. CT scan
features include well-defined lobular mass with heterogenous contrast enhancement
and areas of hypodensity.
Surgery remains the mainstay of treatment for resectable GISTs. Favourable
prognostic features include size less than five cm, complete resection (R0), absence
of perforation and low histological grade. Conversely size greater than five centimetres, tumor necrosis, mitosis greater than 5/50 high power filed, positive
ab
Fig. 48.3 a and b: Mesenteric GIST. Coronal contrast-enhanced computed tomography and axial
T2-weighted magnetic resonance imaging demonstrate an ill-defined, heterogeneously enhancing
GIST (G) with a large cystic component (asterisk). Additional heterogeneous soft tissue along the
periphery of the lesion (oval) is suggestive of peritoneal sarcomatosis and associated ascites (A).
Layering T2-hypointense signal (arrows) is indicative of necrosis with layering blood products.
With permission from Dr. Abraham Dachman and Dr. Justin Ramirez
482 R. Sehgal et al.
resection margins, and distant metastasis are poor prognostic indices. The tyrosine
kinase inhibitor, imanitib mesylate, has been utilized in the adjuvant setting in
patients who present with very large sized tumors that are at high risk of disease
recurrence and metastatic spread. Overall the malignant potential of GIST varies,
with benign tumours having a 5-year survival of 95% in contrast to the malignant
type where it is 21%.
Mesenteric Carcinoid Tumors
Carcinoid tumors are rare neuroendocrine tumors that arise within the gastrointestinal tract in 90% of cases. Gastrointestinal (GIT) tract carcinoid tumors are
classified according to embryologic origin as foregut, midgut and hindgut tumors.
46–64% of GIT carcinoid tumors arise in the midgut and most midgut carcinoid
tumors originate in the terminal ileum, beyond the ligament of Treitz. Primary
mesenteric carcinoid tumors are rare, and while the mesentery is involved in 40
−80% of cases, the majority of carcinoid tumors in the mesentery are metastases.
As mid-gut carcinoid tumors secrete serotonin, patients can develop carcinoid
syndrome with flushing and diarrhoea (especially though not exclusively, when the
tumor has spread to the liver). Furthermore, carcinoid tumors can induce an intense
desmoplastic reaction leading to mesenteric scarring and shortening. This can
sometimes lead to intestinal obstruction, segmental portal hypertension, and chronic
mesenteric ischaemia.
Microscopically, typical carcinoid tumors have one of five growth patterns:
insular, trabe cular, glandular, undifferentiated, or mixed. Most mid-gut carcinoids
have a mixed insular and glandular growth pattern, and express have synaptophysin, chromogranin A, cytokeratins and neuron-specific enolase.
Before a diagnosis of primary mesenteric carcinoid can be made, involvement of
other sites that are more commonly affected sites must be out-ruled by performing
CT of thorax, abdomen and pelvis, colonoscopy, small bowel series and scintigraphy. Abdominal CT and an octreotide scanning may demonstrate a mesenteric
tumor and/or liver metastases. CT scan demonstrates a solitary mass with varying
degrees of fibrosis, calcification, focal or diffuse neurovascular bundle invasion.
A colonoscopy, small bowel series and surgical exploration of the abdomen can
confirm the diagnosis of mesenteric carcinoid.
Surgical excision is a mainstay of treatment for carcinoid tumors. For tumors
smaller than 2 cm without lymph node involvement, local segmental resection is
adequate. Tumors measuring more than 2 cm with regional mesenteric metastasis
and lymphadenopathy are associated with 80–90% incidence of metastasis.
Therefore, wide excision of the bowel and associated mesentery with lymph node
dissection is recommended. Moreover surgical debulking of local or metastatic
tumors is recommended in order to relieve symptoms and prolong survival.
48 Mesenteric Neoplasms 483
Mesenteric Liposarcoma
Sarcomas are a heterogeneous group of malignant tumors which arise from mesenchymal tissues. Liposarcoma is one of the most common histological variants
seen in adults. They can be subdivided into several histological subtypes including
well-differentiated, pleomorphic, round-cell, myxoid and dedifferentiated type. The
well-differentiated subtype are most common, have the highest fat content and are
also referred to as atypical lipoma. Myxoi d lesions are the second most common
and are of intermediate-grade. They are associated with balanced chromosomal
translocation t(12,16). Pleomorphic and round-cell lesions are considered
high-grade and metastasize frequently. Approximately 75% of well-differentiated
liposarcomas develop in the deep soft tissue of the limbs, followed by 20% in the
retroperitoneum and inguinal area. Primary mesenteric liposarcoma is a rare entity,
with less than 30 reported cases in the literature.
Mesenteric liposarcoma more commonly affect males between ages 50 and
70 years. They carry low metastatic potential and are locally aggressive. They are
most commonly deep seated solitary masses located close to the root of the
mesentery. The majority are asymptomatic or present with a mobile abdominal
mass. However they can present with non-specific symptoms such as anorexia,
early satiety, and abdominal distension, and occasionally can cause subacute
intestinal obstruction or volvulus.
CT and MRI scan are the radiological investigations of choice. They provide
detail regarding tumor characteristics, size and relationship to adjacent structures.
Typical CT findings favouring a liposarcoma include inhomogeneous attenuation,
with evidence of significant amounts of soft-tissue within the fatty mass; infiltration
or poor margination; CT houndsfield units greater than the patients normal fats; and
contrast enhancement. Enhancement on CT changes according to the degree of
histological grade. It is reported that well-differentiated liposarcomas are hyperintense on T2-weighted MRI, and that they demonstrate faint or no enhancement. CT
and MRI appearances of well differentiated liposarcoma, especially lipoma-like
tumors resemble those of fat, but those findings may be differentiated from other
types of tumors by their largely lipomatous appearance.
Surgery with wide local resection with adequate margins remains the mainstay
of treatment of localized mesenteric liposarcoma. Com plete surgical resection at the
time of primary presentation is likely to improve long-term survival, as well as
distant recurrence-free survival, and positive surgical margins are the main predictors of local relapse. The role of radiotherapy and adjuvant chemotherapy for
high-risk patients remains unclear. Interestingly Ishiguro et al. demonstrated significant tumor shrinkage by pre-operative chemotherapy using doxorubicin, cisplatin and ifosfamide and that this facilitated a R0 resection. Trabectedin has
emerged as a favourable option for patients with advanced soft tissue sarcomas and
has been approved in the European Union as a second-line option for advanced
previously-treated soft tissue sarcomas.