Small Bowel 3/2012

Front 1

Sclerosing Mesenteritis

Back 1

- Complex inflammatory disorder of the mesentery
- Can be associated with other inflammatory disorders such as Retroperitoneal fibrosis, sclerosing cholangitis, Reidel thyroiditis, orbital pseudotumor
- Exact cause unknown
- Also known as retractile mesenteritis, systemic nodular panniculitis, liposclerotic mesenteritis and xanthogranulomatous mesenteritis

Front 2

Sclerosing Mesenteritis
Clinical Presentation

Back 2

- Pain, obstruction, ischemia, mass, diarrhea
- Elevated ESR
- CT can suggest diagnosis-but usually biopsy needed.

Front 3

Sclerosing Mesenteritis

Back 3

- CT Appearance Varies
- Subtle increased density in mesentery
- Solid mass
- Fibrosis and tethering of small bowel and mesenteric vessels

Front 4

Normal Anatomy
Small Bowel

Back 4

- < 2.5 cm in diameter
- Bowel wall < 3mm: almost imperceptible when distended
- Thin regular folds
- Homogeneous enhancement

Front 5

Capsule Endoscopy

Back 5

Acquires 50K images in 8hours
- Clinicians can visualize the entire small bowel
- Bailey, AJR;101:2237-2243: 426 exams, only 6.3% of 27 small bowel tumors identified on capsule endoscopy were suggested on the prior radiographic exams.
- Especially useful in patients presenting with GI bleeding
- Can miss bowel lesions due to improper bowel preparation, rapid transit time, presence of blood
- Capsule retention or obstruction may occur.

Front 6

Small Bowel Neoplasms

Back 6

- Relatively Rare
- 1-2% of all GI cancers arise in the small bowel
- ACS: estimated 7570 new cases and 1100 deaths due to small bowel cancer in US in 2011
- The US has among the highest age-adjusted incidence of small bowel tumors, worldwide
- Increase in incidence in the US over last 30 years

Front 7

Small Bowel Neoplasms
Risks

Back 7

- Diet.: Eating high-fat foods may raise the risk of small bowel cancer. Regularly consuming smoked or cured foods may also increase a person’s risk.
- Crohn disease.
- Celiac disease.
- Familial adenomatous polyposis (FAP).

Front 8

Small Bowel Neoplasms
Presentation

Back 8

- Pain, nausea, vomiting
- Weight loss, obstruction
- GI bleeding
- Lack of reliable clinical findings
- Usually significant delay in diagnosis

Front 9

Carcinoid Tumor

Back 9

1. Originate from enterochromaffin cells of the neuroendocrine system
2. Classically categorized based on their origin from embryonic divisions of the alimentary tract
- Foregut (lungs, bronchi, stomach)
- Midgut (small bowel, appendix and proximal colon)
- Hindgut (distal colon and rectum)
3. More recently categorized based on malignancy
- Benign, low grade, high grade-using histological differentiation, size, angioinvasion, & infiltration as criteria

Front 10

Carcinoid Tumor

Back 10

- Arise in the bowel wall as a submucosal mass
- Made up of small round regular cells containing a round nucleus and clear cytoplasm. Histologic diagnosis also relies on immunohistochemical stains and electron microscopy.
- The presence of elevated excretion of 5-hydroxyindoleacetic acid (5-HIAA) is suggestive of a functioning carcinoid tumor.

Front 11

Gastrointestinal Stromal Tumors

Back 11

- Mesenchymal tumors which typically arise in association with with the muscularis propria of gastrointestinal tract wall
- Most frequent in the stomach (60%), but also can occur in the small bowel (30%) or elsewhere, including the colon and rectum (5%), esophagus (<5%)
- 5% of small bowel malignancies

Front 12

Gastrointestinal Stromal Tumors

Back 12

- Most occur 50-60 years ( rare < 40)
- Can be familial (present often in 30’s)
Symptoms
- GI bleeding, anemia, abdominal pain, dyspepsia, palpable abdominal mass.
- Nishida et al, 271 patients with stromal tumors, 2/3 had symptoms that correlated with tumors size. Tumors > 3 cm were more likely to demonstrate necrosis than tumors < 3 cm.
- Obstruction is rare. Burkhill et al, 1/ 61 SBO

Front 13

Gastrointestinal Stromal Tumors

Back 13

- Arise pathologically from the wall of the GI tract and can be characterized as benign, borderline, low or high malignant potential based on the pathologic appearance.
- The vast majority express a mutant form of c-kit (CD117) that can be detected on routine staining.
- C-kit is a growth factor receptor with tyrosine kinase activity. It is thought that mutations in the c-kit gene are causative for the development of gastrointestinal tumors. It is found in both benign and malignant GIST.

Front 14

Gastrointestinal Stromal Tumors

Back 14

- Characterized as benign, borderline, low or high malignant potential based on the pathologic appearance.
- The vast majority express a mutant form of c-kit (CD117) that can be detected on routine staining.
- C-kit is a growth factor receptor with tyrosine kinase activity. It is thought that mutations in the c-kit gene are causative for the development of gastrointestinal

Front 15

GIST

Back 15

CT Findings
- intramural mass when small
- Can grow endoluminal or exophytic
- often central ulceration and /or necrosis
- do not usually produce significant adenopathy
- 3D CT is especially useful in determine organ of origin

Front 16

Gastrointestinal Stromal Tumors

Back 16

10-30% are malignant
Malignant risk increases with
- Extragastric location
- Size > 5cm
- Extension into adjacent organs
- > 1 mitosis per 50 high powered field