- Pictorial Review
- Open Access
Common primary tumours of the abdomen and pelvis and their patterns of tumour spread as seen on multi-detector computed tomography
© European Society of Radiology 2011
- Received: 13 November 2010
- Accepted: 14 March 2011
- Published: 14 April 2011
Multidetector computed tomography (MDCT) has become the main investigation of choice for staging of many cancers.
The purpose of this pictorial review is to discuss the imaging appearances on CT of some of the more common cancers arising within the abdomen and pelvis and to describe their typical sites of local, nodal and haematogenous tumour spread.
Cancers arising from the stomach, pancreas, colon, kidney, ovary and prostate will be reviewed.
Awareness of the characteristic sites of tumour spread is important to allow accurate identification of all sites of disease.
This will clearly have an impact on both patient management and prognosis.
- Multidetector CT
In the last 2 decades, cross-sectional imaging, in particular multidetector computed tomography (MDCT), has become the main investigation of choice in the locoregional and distant staging of many tumours within the abdomen and pelvis. MDCT benefits from having a high spatial resolution and fast acquisition time, making it an ideal tool to stage and restage tumours. The routine use of intravenous (and oral contrast) media, unless contraindicated, also helps to delineate sites of disease, especially within solid organs. The identification of nodal involvement on CT is based on nodal size, typically using a minimum cutoff of 1 cm in short axis diameter, although this can lead to both under- and over-staging of metastatic nodal involvement. The purpose of this pictorial review is to discuss the imaging appearances on CT of some of the more common cancers arising within the abdomen and pelvis and to describe their typical sites of local, nodal and haematogenous tumour spread. Cancers arising from the stomach, pancreas, colon, kidney, ovary and prostate will be reviewed, with summary tables provided. Lymphoma will not be specifically discussed.
Summary table of local, nodal and haematogenous spread in gastric cancer
•Local spread into adjacent structures (e.g. pancreas, colon, spleen)
Lymph node spread
•Perigastric: pericardial; lesser curvature; greater curvature; suprapyloric
•Extraperigastric: left gastric; common hepatic; coeliac; splenic hilum and artery; hepatic pedicle; retropancreatic; mesenteric root; middle colic; para-aortic
•Most commonly the liver (25% at presentation) and peritoneum
•Transcoelomic spread can occur through the peritoneum (e.g. Kruckenberg tumours)
•Retropancreatic, para-aortic and mesenteric nodes are classified as M1 metastatic disease
•Nodal disease in GIST tumours is extremely rare
Spread to perigastric and less frequently other intra-abdominal nodes may occur (Table 1; Fig. 1). Troisier’s sign describes the clinical finding of an enlarged left supraclavicular lymph node due to metastatic involvement. Abdominal cancers may metastasise to this site via the thoracic duct, and gastric malignancy is classically described as the commonest primary tumour to do this. Obstructive jaundice with associated bile duct dilatation may occur, due to enlarged porta hepatis nodes or due to the spread of gastric tumour via the gastrohepatic ligament directly into the liver.
Haematogeneous spread via the portal vein to the liver occurs in 25% of patients at presentation, with liver metastases typically appearing as rim-enhancing low-attenuation lesions during the portal venous phase. Peritoneal spread occurs in a similar percentage at presentation. Peritoneal disease secondary to gastric adenocarcinoma may mimic the appearance of peritoneal disease secondary to metastatic ovarian carcinoma, with omental cake and/or discrete peritoneal deposits noted within the abdominal cavity. Trans-coelomic spread is also characteristic of gastric cancer, with spread to the ovary resulting in a Krukenberg tumour that typically appears as a mixed solid/cystic adnexal mass. Involvement of the peritoneal reflection within the pelvis can result in a positive Blumer’s shelf finding, with tumour found high on the anterior rectal wall .
Summary table of local, nodal and haematogenous spread in pancreatic cancer
•Tumour spreads by direct perivascular and perineural invasion;
•Local invasion can involve the stomach, duodenum and retroperitoneum;
•Head/uncinate process tumours: these usually extend along the SMA and mesenteric root;
•Body/tail tumours: these usually infiltrate the celiac, hepatic or splenic arteries
Lymph node spread
•Primary drainage: superior, inferior, anterior, posterior and splenic lymph nodes;
•Secondary drainage: porta hepatis, common hepatic, coeliac, mesenteric root lymph nodes;
•Tertiary drainage: peri-aortic and distal superior mesenteric lymph nodes
•These usually involve the liver and peritoneal surfaces
•Early lymphatic and haematogenous micrometastases at presentation are common
When performing a staging CT, ideally at least two contrast-enhanced acquisitions (during the late arterial and venous phases) are advised. Again oral contrast with water is helpful to allow delineation of the duodenal wall.
Spread to regional nodes occurs, involving either peripancreatic nodes, nodes at the celiac axis and porta hepatis, or sometimes nodes further afield (Table 2). Haematogeneous spread also arises, with involvement of the liver and peritoneal surfaces. Distant metastases are found in more advanced cases.
Summary table of local, nodal and haematogenous spread in colorectal cancer
•Invasion through the bowel wall into the peri-colonic fat and adjacent structures
Lymph node spread
•Follows the vascular distribution of vessels in mesocolon;
•Ascending mesocolon: nodes along the ileocolic vessels and right colic vessel;
•Transverse mesocolon: nodes along the middle colic vessels;
•Sigmoid and descending mesocolon: nodes along the inferior mesenteric vein;
•Regional lymph nodes for rectal cancers include: mesorectal, sigmoid mesenteric, inferior mesenteric, lateral sacral, presacral, internal iliac, sacral promontory, superior rectal, middle rectal and inferior rectal
•Liver (via the portal vein) > lung, adrenal glands, bones
•In rectal cancers that have perforated the peritoneum, transcoelomic spread favours the lower right small bowel mesentery and the pouch of Douglas
Metastatic disease at presentation is uncommon (<10–15% of cases). Haematogeneous spread is predominantly seen within the liver, with metastases deriving their blood supply from the hepatic artery (compared to normal liver parenchyma, which is primarily supplied by the portal vein). As a result, liver metastases imaged during the portal venous phase are seen as heterogeneous ring-enhancing metastases that are hypodense to the surrounding liver parenchyma (Fig. 4b). If the primary cancer is mucinous, liver metastases may be cystic or calcified. Sites of distant metastases are determined by the venous drainage of the primary site . For example, the venous drainage of the colon and upper rectum is via the portal vein, and thus the liver is a common site of spread. However, the lower rectum has a dual drainage, with the superior haemorrhoidal vein draining into the inferior mesenteric vein and then into the portal vein, and the middle and inferior haemorrhoidal veins draining into the pelvic veins and then directly into the inferior vena cava. This explains why distal rectal cancers can result in isolated pulmonary metastases without hepatic metastases.
Renal cell carcinoma (RCC)
Summary table of local, nodal and haematogenous spread in renal cell carcinoma
•Perinephric fat; ipsilateral adrenal; adjacent viscera (including muscles);
•Renal vein invasion (± IVC)
Lymph node spread
•Via lymphatics following the renal vessels to the ipsilateral para-aortic nodes; direct connections with the thoracic duct and mediastinum also exist
•Common sites: lungs > bones, CNS, adrenals
•Extension into renal vein occurs in 20% of patients at presentation; IVC involvement in 5–10%
Lymphatic spread from RCC tends to follow the renal veins to involve the ipsilateral para-aortic nodes. There are also direct connections with the thoracic duct and mediastinum, which can account for the rare presence of mediastinal and hilar node involvement (Fig. 7a) at presentation (especially on the right side).
Between 25–35% of patients with RCC have metastases at diagnosis . Metastatic involvement in renal cell carcinoma is seen (in order of decreasing frequency) in: the lung (50–60%), bone (30–40%), liver (30–40%), adrenal gland (5%), contralateral kidney (5%), retoperitoneum (5%) and brain (5%) . More unusual sites that have been reported include the pancreas, peritoneum, bowel, thyroid and muscle (Fig. 7b) and subcutaneous tissues. Visceral metastases tend to be hypervascular, similar to the primary tumour. Bony involvement appears as expansile lytic lesions within the axial skeleton (Fig. 7c).
Summary table of local, nodal and haematogenous spread in ovarian carcinoma
•Uterus and broad ligament (via the fallopian tube);
•Direct invasion of the rectum, colon, bladder and pelvic side wall
Lymph node spread
•Via lymphatics travelling along with the ovarian vessels to terminate in common iliac and para-aortic nodes;
•Via the broad ligament to terminate in the internal iliac and obturator nodes;
•Via the round ligament to terminate in the external iliac and inguinal nodes
•Common sites: undersurface of the diaphragm, liver surface, pouch of Douglas, omentum, serosal bowel surfaces
•This occurs late during the disease;
•Liver > lungs, kidney, bone
•Ascites arise from increased production from tumour surfaces and/or occlusion of retroperitoneal lymph nodes
Peritoneal dissemination is the commonest mode of spread, being found in approximately 70% of patients at presentation. Common sites include the greater omentum, paracolic gutters, the pouch of Douglas, the liver capsule (Fig. 8b), the diaphragm and bowel serosa. Less commonly, implants may be seen within the mesentery, along the porta hepatis, lesser sac, splenic surface and gastrosplenic ligament [16–18]. Ascites are often present, due to either increased production from tumour surfaces or reduced peritoneal resorption from invasion of lymphatics by tumour cells. Peritoneal deposits on CT have a variety of appearances including enhancing nodular soft tissue lesions, linear/plaque-like thickening of peritoneal reflections (Fig. 8a), thick omental cakes (Fig. 8c), tiny calcifications or mixed solid and cystic or purely cystic lesions [19, 20]. The involvement of bowel serosa can lead to (asymmetric) bowel wall thickening, tethering of bowel loops and bowel obstruction. Liver surface implants (subcapsular deposits) may be seen, with deposits causing characteristic scalloping of the liver capsule. Metastatic mucinous tumours of the ovary can lead to pseudomyxoma peritoneii, although in many of these cases, the primary mucinous tumour actually arises from the gastrointestinal tract with secondary involvement of the ovary.
Lymphatic spread occurs via three routes and is usually seen in conjunction with peritoneal spread. Routes include: (1) along the ovarian vessels to the common iliac and para-aortic nodes (Fig. 8a); (2) via the broad ligament and parametria to the internal iliac and obturator nodes; and (3) rarely via the round ligaments to the external iliac and inguinal nodes. Cardiophrenic nodes (defined as >5 mm short axis diameter on CT)  are characteristically involved as they are the main lymphatic drainage route from the peritoneal cavity (Fig. 8d).
Haematogenous dissemination is rare in ovarian carcinoma with a malignant pleural effusion being the most common manifestation. At presentation, liver metastases are seen in less than 1% of cases. Other sides of spread include the spleen, kidneys, adrenals, lungs, brain and bone.
Summary table of local, nodal and haematogenous spread in prostate cancer
•Direct extension through the prostate capsule into the seminal vesicles and bladder base
Lymph node spread
•Order of nodal involvement: obturator, presacral, internal iliac, common iliac
•Bone >> lung and liver;
•Spinal bone metastases are the commonest site (due to the direct communication between the presacral and periprostatic veins)
•Denonvillier’s fascia forms a relative natural barrier to rectal spread;
•Tumours at the apex of the prostate are more likely to demonstrate extracapsular extension because of relatively little capsule at this level
Distant spread occurs in one third of patients with involved sites including bone (90%), lung (50%), liver (25%) (Fig. 9a), pleura (21%) and adrenals (13%) . Osteoblastic sclerotic metastases rather than lytic bone lesions are usually seen on CT. In order of decreasing frequency, skeletal metastases are seen within the vertebrae (Fig. 9b), sternum, pelvic bones, ribs and femora. Spinal involvement is initially more common within the lumbar region and less likely within the cervical spine (97% cf. 38%), suggestive of upward metastatic spread along the spinal veins . Pulmonary metastases occur in between 5–27% of patients at presentation  and are more often seen in association with the second pattern of nodal involvement . Pulmonary involvement can either appear as lymphangitis carcinomatosa (due to direct invasion of the pulmonary lymphatics) or as pulmonary nodules (due to haematogenous spread) [22, 24].
This review has described the typical patterns of tumour spread for the more common cancers occurring within the abdomen and pelvis. Sites of nodal and haematogenous dissemination clearly vary depending on tumour type. Knowledge of the characteristic sites of spread in such cancers is felt to be essential for the radiologist when reporting staging and restaging CT scans. It is hoped that the summary tables in particular will act as a useful aide-mémoir to the reporting radiologist. Correct identification of metastatic sites of disease is important, as this will not only have an impact on patient management, but also a bearing on patient prognosis.
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