Small Bowel Tumours

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DEFINITION

Tumours of small bowel are uncommon and their manifestations vary according to specific types of tumours.

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EPIDEMIOLOGY

Rare; 2% of digestive tract cancers per year.
Often older pts 60-80y

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AETIOLOGY

Why are they rare?
Various propositions:
- rapid transit, low bacterial load, high lymph tissue, rapid turnover
- less inflammation as SB chyme is liquid and alkaline

Types

1. Carcinoid / NET (most common)
2. AdenoCa (second; ~33%)
3. GIST
4. Lymphoma
5. Metastases
6. Benign Tumours

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BIOLOGICAL BEHAVIOUR

1. Carcinoid / NET
See NET notes

2. AdenoCa
Commonly in duodenum
Associated with Crohn's, coeliac, FAP, HNPCC and Peutz-Jegher
>50% have advanced disease at presentation.
- one quarter with mets.

3. GIST
See GIST notes

4. Lymphoma
i.e. Non-Hodgkin
See lymphoma notes

5. Metastases
Mainly from melanoma, lung, and breast
Via direct invasion, haematogenous or lymphatic spread
- and intra-peritoneal seeding

6. Benign Tumours

Adenomas
- see polyp notes
Similar to colonic adenomas
- tubular, tubulovillous and viloous.
High risk of malignant transformation if >1cm
- or high grade of dysplasia and villous subtype.
- 1/3 of duodenal villous tumours excised harbour malignancy
FAP = high prevalance
- periampullary cancer now leading cause of death in FAP

Lipoma
Little or no malignant potential and unlikely to cause obstruction

Hamartoma
Smooth muscle core arising from muscularis mucosa and extending into polup
Often multiple
Characteristic of Peutz Jegher
- occur throughout bowel and in varying number; up to hundreds
- In PJ can be associated with higher risk of AdenoCa

Hemangioma
Rare masses, capillaries or blood-filled endothelial-lined spaces
Local excision of segmental resection, endoscopic treatment if within reach.
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MANIFESTATIONS

1. Carcinoid / NET
See NET notes

2. AdenoCa
Depends on location and extent of disease
Possible features include obstruction, abdo pain, and biliary obstruction.

3. GIST
See GIST notes

4. Lymphoma
i.e. Non-Hodgkin
See lymphoma notes

5. Metastases
Most common presentation = small bowel obstruction
Ascites, mesenteric ischaemia and perforation and bleeding also occur.

6. Benign Tumours
Often go undetected.
May obstruct, bleed or intussucept.
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INVESTIGATIONS

Imaging
SB least accessible part of tract; historically difficult
CT, SB follow through, MRI, push enteroscopy and pillcam are all options.
- pillcam advantage of being less invasive; but can't biopsy and

AdenoCa
Periampullary lesions identified on upper endoscopy.
EUS, MRCP useful.
Cancers distal to ligament of Treitz are amenable to video endoscopy and double-balloon enteroscopy
Advanced tumours may appear as apple-core lesions
- short annular narrowed portions with ulceration and rigid.
CT - often show as protruding polyps or circumferential masses, like bowel tumours.

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MANAGEMENT

1. Carcinoid / NET
See NET notes

2. AdenoCa
Only potential cure remains surgical resection.
Whipples for periampullary lesions
Distal duodenal cacner treated with segmental resction and lymphadectomy.
Jejunal and ileal tumours with segmental resection, wide lymphadenectomy
Terminal ileum tumours with ileocolectomy.
Metastatic disease: palliation including bypass; stents if possible.
5 year survival is 30%, median 20months.
Negative factors:
Males, age>55, duodenum or ileum and obviously distant mets

3. GIST
See GIST notes

4. Lymphoma
i.e. Non-Hodgkin
See lymphoma notes

5. Metastases
Advanced disease so fairly conservative approach warranted.
Treat SBO like any SBO and resect if disease and patient factors warrant it.

6. Benign Tumours
Adenoma
Endoscopic evaluation and biopsy surveillance
- but may miss cancer.
Local excision appropriate for small tumours, EMR.
- Villous = local excision to pancreas-sparing duodenectomy to Whipple's.
- If no ulceration, severe dysplasia or dilation of pancreatic and CBD = may be treated with local excision.
If recur, be more aggressive.
FAP and duodenal tumours with high grade dysplasia warrant surgery (pancreas sparing or not).
Lipoma
On CT = homogenous mass, radiolucent, well circumscribed.
Size and form change with peristalsis and pressure.
Small ones can be treated conservatively, large ones >2cm = resect.
Hamartomas
Invasive treatment limited to removing symptomatic polyps or those rapidly enlarging.




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REFERENCES

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