thai j g 2016 x-ray vol. 17 no. 3 corner · it shares epidemiologi-cal and pathological features...

THAI J GASTROENTEROL 2016Vol. 17 No. 3

Sep. - Dec. 2016187

Pantongrag-Brown L

Imaging of The Peritoneum and Mesentery

Pantongrag-Brown L

Advanced Diagnostic Imaging Center, Ramathibodi Hospital, Bangkok, Thailand.

Address for Correspondence: Linda Pantongrag-Brown, M.D., Advanced Diagnostic Imaging Center, Ramathibodi

Hospital, Bangkok, Thailand.

X-rayCorner

Figure 1. Case 1.

Modern imaging modalities commonly used in

peritoneum and mesentery include ultrasound (US),

CT, and MRI. US is good for detection of ascites, but

may be a limited tool for finding the etiologies of peri-

toneal and mesenteric diseases. CT or MRI is usually

needed for further investigation. CT is slightly favo-

rable to MRI for visualization of intra-abdominal ca-

vity. This is because MRI is sensitive to bowel peri-

stalsis and severe motion artifact may obscure the de-

tail within the peritoneal cavity. In this article, several

peritoneal and mesenteric abnormalities will be

demonstrated, using case-based approach, and empha-

sizing on imaging findings.

Case 1. A 47-year-old woman presenting with

abdominal distension.

THAI JGASTROENTEROL

2016188


Figure 2. Case 2.

Axial views of CT scan show multiple lymphad-

enopathy surrounding the abdominal aorta, giving the

appearance of “floating aorta sign”. Some of large

nodes show low-density necrosis. Minimal ascites is

observed. D/Dx of multiple intra-abdominal lymphad-

enopathy includes lymphoma, metastasis, and TB. The

appearance of necrotic nodes gives TB the most likely

diagnosis. Nodal biopsy reveals caseous necrosis with

positive acid fast bacilli. Final diagnosis is TB perito-

nitis.

The floating aorta sign refers to displacement of

the abdominal aorta away from the vertebral column.

Any retroperitoneal mass arising posterior to the aorta

can insinuate between the aorta and the vertebral col-

umn, and displace the aorta anteriorly; hence the term

floating aorta sign. It is a radiographic/ CT sign of ret-

roperitoneal mass or lymphadenopathy(1).

The abdomen is the most common site of extra-

pulmonary tuberculosis, and peritoneal disease is the

most common form within the abdomen. Abdominal

tuberculosis can also involve the solid organs, gas-

trointestinal tract, mesentery and lymph nodes(2). CT

imaging features seen with tuberculous peritonitis in-

clude nodular thickening of the peritoneum and me-

sentery, abnormal peritoneal or mesenteric enhance-

ment, ascites, and low attenuating lymphadenopathy.

Low-density lymphadenopathy is secondary to caseous

necrosis and is a clue for prospective diagnosis of TB.

Case 2. A 46-year-old woman presenting with

abdominal distension.

Axial views of CT scan show nodular thickening

of the peritoneum; nodular depositions along the liver

surface, gastrohepatic ligament, and gastrosplenic liga-

ment (thick arrows). Ascites and a thick omental cake

are observed (thin arrows). Findings are consistent with

peritoneal carcinomatosis. Primary tumor is ovarian

cancer showing as a large, lobulated contour mass

within the pelvis.

Differential diagnosis of omental cake includes

peritoneal carcinomatosis, pseudomyxoma peritonei,


Sep. - Dec. 2016189

Pantongrag-Brown L

peritoneal mesothelioma, peritoneal lymphomatosis,

primary peritoneal serous carcinoma, and peritoneal

TB. Searching for primary tumor within the abdomen

will help pinpoint diagnosis towards carinomatosis

peritonei, such as in this case. Common primaries in-

clude ovarian cancer, GI tract malignancy, breast can-

cer, lung cancer, and malignant melanoma(3).

Figure 3. Case 3.

Axial views of CT scan show multiple homoge-

neous, bulky lymphadenopathy involving diaphrag-

matic, mesenteric and peri-aortic region. The aorta is

lifted above the vertebral body, giving the appearance

of the “floating aorta sign”. The stomach shows irregu-

lar thickened wall (arrow). Moderate amount of ascites

is noted. D/Dx of multiple intra-abdominal lymphad-

enopathy includes lymphoma, metastasis, and TB. The

appearance of bulky, homogeneous lymphadenopathy

gives lymphoma the most likely diagnosis. Biopsy of

the stomach confirms the diagnosis of lymphoma.

Lymphoma can present as nodal or extra-nodal dis-

ease. Multiple sites and multiple organs of involve-

ment are hallmark of lymphoma. The etiology is un-

known but potential risk factors include viral infection

(e.g. EBV, HTVL-1, HIV, HCV, HSV), bacterial in-

fection (e.g. Helicobacter pylori), and chronic immu-

nosuppression (e.g. post-transplantation)(4). Lymphoma

is classified into Hodgkin lymphoma, and non-Hodgkin

lymphoma. Imaging characteristics will depend on the

location and subtype of lymphoma. CT is usually the

imaging of choice for staging of lymphoma.

Case 3. A 47-year-old man, presenting with abdominal pain.

THAI JGASTROENTEROL

2016190


Case 4. A 57-year-old man presenting with abdominal pain and weight loss.

Axial views of CT scan shows marked thickened

wall of the stomach (thin arrow) with multiple mesen-

teric lymphadenopathy. A large omental cake (thick

arrow) displaces bowel loops inwardly. Minimal as-

cites is noted.





TB. In this case, an irregular gastric mass, associated

with lymphadenopathy makes lymphoma, and primary

gastric cancer with nodal metastasis the most likely

diagnosis. Biopsy of the gastric wall reveals primary

Figure 4. Case 4.

adenocarcinoma.

Adenocarcinoma is the most common gastric ma-

lignancy, representing over 95% of malignant tumors

of the stomach(5). Endoscopy is regarded as the most

sensitive and specific diagnostic method in patients

suspected of gastric cancer. Endoscopy allows direct

visualization of the tumor, and biopsy for tissue diag-

nosis. However, imagings are often the initial exami-

nation that raise suspicion for gastric carcinoma. More-

over, CT is currently the modality of choice for stag-

ing, because it can help identify the primary tumor,

assess the local spread, and detect nodal involvement

and distant metastasis.

Case 5. A 65-year-old man presenting with abdominal pain and distension.

Figure 5. Case 5.


Sep. - Dec. 2016191

Pantongrag-Brown L

Axial views of CT scan show massive ascites with

calcified, thick pleural plaque (thin arrow). Omental

cake and peritoneal depositions (thick arrows) are ob-

served. Small bowel loops are matted and conglomer-

ated in the central abdomen.





TB. In this case, a calcified pleural plaque is a clue of

possible asbestos exposure or chronic infection. There-

fore, peritoneal mesothelioma or TB peritonitis is the

most likely diagnosis. Biopsy of the omental cake re-

veals peritoneal mesothelioma.

Peritoneal mesothelioma is an uncommon primary

tumor of the peritoneal lining. It shares epidemiologi-

cal and pathological features with but is less common

than its pleural counterpart. As with pleural mesothe-

lioma, there is also a strong association with asbestos

exposure. Presence of calcified pleural or peritoneal

plaque is an important characteristic of asbestos expo-

sure. Peritoneal mesothelioma is a malignant tumor but

tend to be localized. Metastasis to distant organs and

lymphadenopathy are uncommon(6).

US and CT scan show multiloculated cysts in-

volving the entire lower abdomen. The cysts insinuate

around the tissue and does not cause small bowel ob-

struction. D/Dx of multiloculated cysts in a relatively

young female include cystic mesothelioma, lymphan-

gioma, and cystic tumor of the ovary. Biopsy of the

lesion confirms the diagnosis of cystic mesothelioma.

Cystic mesothelioma is relatively rare and occur

predominantly in young to middle-aged women. In

contrast to malignant peritoneal mesothelioma, this

tumor has no association with asbestos exposure, but

it is commonly associated with a history of previous

abdominal surgery or pelvic inflammatory disease. In-

volvement of the pelvic region is characteristic. Cystic

mesothelioma is considered benign but recurrence is

common after surgical resection(7).

Figure 6. Case 6.

Case 6. A 35-year-old female presenting with abdominal discomfort.

THAI JGASTROENTEROL

2016192


Case 7. A 73-year-old man presenting with abdominal mass.

to a metastasis from a carcinoid tumor of the small

bowel beyond the ligament of Treitz. Primary carci-

noid tumor of the mesentery is rare. Indeed, its exist-

ence is questionable, because the primary site within

the small bowel could be occult. The nidus of tumor

growth within the mesentery is probably lymph node.

The characteristic CT finding is a triad of a calcified

mesenteric mass, radiating strand, and adjacent bowel-

wall thickening(8). The linear radiating strands observed

in the mesentery are due largely to the fibrotic pro-

cess. This profound desmoplastic response is caused

by hormonally active substances, especially serotonin,

secreted by carcinoid tumor. These same hormones also

provoke desmoplastic effects within the bowel wall and

along the mesenteric vessels, resulting in ischemia and

edema of the surrounding small bowel loops.

Small bowel follow-through study shows dilated

and thickened small bowel loops encircling around a

soft-tissue lesion. CT scan shows a calcified mesen-

teric mass, associated with surrounding linear

strandings, radiating from the central calcification to

the adjacent small bowel loops. Surrounding small

bowels show diffuse thickened wall and tethering to-

wards linear strandings.

D/Dx of calcified mesenteric mass includes me-

senteric carcinoid, retractile mesenteritis, lymphoma,

and metastasis. The triad of a calcified mesenteric mass,

radiating strands, and adjacent bowel-wall thickening

is highly suggestive of carcinoid tumor. Surgery was

performed and pathology confirms the diagnosis of me-

senteric carcinoid.

Mesenteric carcinoid tumor is almost always due

Figure 7. Case 7.


Sep. - Dec. 2016193

Pantongrag-Brown L

Small bowel follow-through study shows a large

abdominal mass displacing small bowel loops peri-

pherally. CT scan confirms a large, well-defined mass

with relatively homogeneous density and moderate vas-

cularity. D/Dx of a large mesenteric mass includes

desmoid tumor, mesenteric sarcoma (e.g. leiomyosar-

coma, liposarcoma, MFH), and lymphoma. Surgery

was performed and proved to be a desmoid tumor.

Desmoid tumor is derived from musculo- apo-


neurotic structures throughout the body. In spite of its

large size, the tumor tends to be homogeneous and well-

defined on CT, which is an important clue to diagno-

sis. In the mesentery, the mass may occur sporadically

or be associated with familial adenomatous polyposis

(FAP) and Gardner syndrome. Desmoid tumor has a

tendency to recur, even after complete surgical resec-

tion(9).


Figure 8. Case 8.

Figure 9. Case 9.

THAI JGASTROENTEROL

2016194


Axial views of CT scan shows a large mesenteric

mass, displacing small bowel loops peripherally. The

mass contains fatty strands (arrow). D/Dx of a large

mesenteric mass includes desmoid tumor, mesenteric

sarcoma (e.g. leiomyosarcoma, liposarcoma, MFH),

and lymphoma. A fatty strands within the mass are sug-

gestive of liposarcoma. Surgery was performed and

proved to be liposarcoma.

Liposarcoma is a malignant tumor of fatty tissue

and is the malignant counterpart to a benign lipoma.

Liposarcoma is thought to originate from mesenchy-

mal cells, and retroperitoneum is the most common

site within the abdomen. Primary mesenteric liposar-

coma is rare. Among the malignant mesenteric tumors,

lymphoma is the most common followed by leiomyo-

sarcoma. The treatment of choice for liposarcoma is

surgical excision with appropriate margins followed

by radiation with or without adjuvant chemotherapy

in high risk patients(10).

CONCLUSIONS

Nine cases of peritoneal and mesenteric diseases

are illustrated, emphasizing on the imaging appear-

ances. These cases are as following:

1. Neoplastic pathology:

a. Peritoneal carcinomatosis, primary ovarian

cancer

b. Peritoneal carcinomatosis, primary gastric

cancer

c. Peritoneal mesothelioma

d. Cystic mesothelioma

e. Lymphoma

f. Mesenteric liposarcoma

g. Mesenteric carcinoid tumor

h. Mesenteric desmoid tumor

2. Infectious/inflammatory pathology:

a. Peritoneal TB

REFERENCES

1. Havrilla TR, Reich NE, Haaga JR. The floating aorta in com-

puterized tomography: a sign of retroperitoneal pathology. Clin

Imag 1977. p. 107-10.

2. Suri S, Gupta S, Suri R. Computed tomography in abdominal

tuberculosis. Br J Radiol 1999;72: 92-8.

3. Levy AD, Shaw JC, Sobin LH. Secondary tumors and tumor-

like lesions of the peritoneal cavity: imaging features with

pathologic correlation. Radio Graphics 2009; 29:347-73.

4. Frampas E. Lymphomas: Basic points that radiologists should

know. Diagn Interv Imaging 2013;94:131-44.

5. Horton KM, Fishman EK. Current role of CT in imaging of

the stomach. Radio Graphics 2003;23:75-87.

6. Park JY, Kim KW, Kwon H, et al. Peritoneal Mesotheliomas:

clinicopathologic features, CT findings, and differential diag-

nosis. AJR 2008;191:814-25.

7. Weiss SW, Tavassoli FA. Multicystic mesothelioma: an analy-

sis of pathologic findings and biologic behavior in 37 cases.

Am J Surg Pathol 1988;12:737-46.

8. Pantongrag-Brown L, Buetow PC, Carr NJ, et al. Calcifica-

tion and fibrosis in mesenteric carcinoid tumor: CT findings

and pathologic correlation. AJR 1995;164:387-91.

9. Faria SC, Iyer RB, Rashid A, et al. Desmoid tumor of the

small bowel and the mesentery. AJR 2004; 183:118.

10. Jain SK, Mitra A, Kaza RCM, et al. Primary mesenteric li-

posarcoma: an unusual presentation of a rare condition. J

Gastrointest Oncol 2012;3:147-50.

thai j g 2016 x-ray vol. 17 no. 3 corner · it shares epidemiologi-cal and pathological features...

Documents