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22 Cards in this Set

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1. What are the imaging manifestations of graft versus host disesae (GVHD)?
2. In what patient population is this complication seen?
3. What other processes can mimic this appearance?
1.graft versus host disease is marked, multisystemic inflammation usually occurring within 100 days after bone marrow transplant. Pathogenesis is believed to be severe, acute enteritis caused by an immune response mounted by the transplanted lymphocytes against the host tissue.
- Circumferential wall thickening of the small bowel that can involve the entire GI tract, but disease is predominantly seen in ileum and colon.
- Tubular narrowing (ribbon like bowel) and loss of mucosal markings (featureless)
- Mucosal ulceration with intramural dissection of barium.
- Can eventually develop strictures.
2. 30-70% of patients with allogenic transplant (AML)
3. Radiation enteritis(usually more localized as it involves structures within the radiation port) and infection by cytomegalovirus or Cryptosporidium.

graph versus host disease can be exacerbated by a host of opportunistic infections due to the underlying immunocompromise.
What is the differential diagnosis of terminal ileum wall thickening?
INFLAMMATORY:
- Crohn’s disease
- UC with backwash ileitis
INFECTIOUS:
- Appendicitis or diverticulitis with adjacent inflammation
- TB
- Yersinia
- Amoebiasis (preferentially involves cecum with sparing of TI)
NEOPLASTIC:
- Lymphoma
- AdenoCA (less common)
IATROGENIC:
- GVHD
What are the imaging findings in scleroderma affecting the small bowel?
- Dilated small bowel due to replacement of smooth muscle by fibrosis.
- Tightly packed folds of valvulae conniventes of normal thickness = hide-bound bowel sign
- Small bowel sacculations (pseudodiverticula) -- can mimic Crohn's disease with asymmetric involvement.
- does NOT result in wall thickening
1. What are the imaging findings of shock bowel?
"Shock bowel" would appear as diffuse submucosal edema
1. What are imaging features of small bowel vasculitis?
2. What is hereditary angioedema and what are its imaging findings?
1. Henoch-Schönlein purpura and others are types of vasculitis that could cause bowel wall hemorrhage and/or edema, as well as luminal narrowing.

2. Angioedema can produce small bowel wall thickening. Check for C1 esterase deficiency and a use of ACE (angiotensin converting enzyme) inhibitors to diagnose.
What are the benign tumors of the small bowel?
1. Polyp: can be solitary or multiple (assoc with polyposis syndromes)
2. Hemangioma: can be solitary or multiple.
3. GIST: after the stomach and esophagus, the jejunum is the most frequent site of GIST.
4. Lipoma: pliable, soft. Easily dx'ed by CT when fat density is seen. Can be multiple.
What are the malignant tumors of the small bowel?
1. Adenocarcinoma: MC in the duodenum. Often presents as an "apple core lesion". Increased incidence in celiac disease.
2. Lymphoma: mostly NHL. Can present as solitary, multiple, infiltrative, or excavated mass
3. Mets: usually multiple.
4. Carcinoid: usually distal SB; primary lesion usually not seen with meseteric mets eliciting a desmoplastic reaction.
5. Malignant GIST: submucosal mass; look for liver mets.
What are the imaging findings of gallstone ileus?
Look for multiple dilated loops of small bowel with pneumobilia and possible stone in the small bowel. The gallstone usually impacts in the TI. Obstructing stones usually are not spontaneously passed and require surgical lithotomy.
1. What is the most common location for a duplication cyst?
2. Do duplication cyst communicate with the lumen of the small bowel?
3. What can they mimic on nuclear medicine gastric bleeding scan?
1. Terminal ileum
2. It may or may not communicate with the lumen.
3. May contain ectopic gastric mucosa and mimic a Meckel's diverticulum.
1. What is exoenteric growth?
2. What tumors can demonstrate this type of growth?
3. Do malignant GIST metastasize to lymph nodes?
1. Exoenteric growth is characterized by tumors that start off in the bowel wall but grow into the mesentery. The tumor destroys the bowel wall, forming a large cavitated mass devoid of mucosal markings.
2. Lymphoma, malignant GIST, melanoma mets, and occasionally colon cancer.
3. Malignant GIST tumors do not metastasize to lymph nodes. Look for hepatic mets in GIST. NOTE: the stomach is the most common location for GIST, followed by the duodenum.
1. What is the DDX of multiple small bowel masses?
2. What is the complication of any mass in the small bowel?
3. What tumors commonly metastasize hematogenously to the small bowel?
Benign causes of mutliple small bowel masses: polyps, lipomas, hemangiomas.
Malignant causes of multiple small bowel masses: mets, lymphoma.
2. Lead point for intussusception.
3. Melanoma, lung, breast, Kaposi.
1. What are the imaging characteristics of small bowel lymphoma?
2. What is the most common location for small bowel lymphoma?
3. How does HL differ from NHL when involving the small bowel?
4. What are the risk factors for small bowel lymphoma?
5. What other tumors can mimic lymphoma of small bowel?
1. Typically, lymphoma presents as multiple masses. It can affect long segments of small bowel leading to wall thickening and aneurysmal dilatation. Sometimes, lymphoma can grow outside the bowel lumen (exoenteric growth) or a nodal mass can invade the small bowel wall.
2. Distal small bowel, typically the terminal ileum, as most lymphoid tissue is located distally. It can cross the ileocecal valve and affect the cecum.
3. HL is less common than NHL. HL can incite a desmoplastic reaction producing luminal
narrowing and possibly obstruction. It does not result in aneurysmal dilatation seen with NHL. Because NHL does not incite a desmoplastic reaction, the bowel is at risk for perforation.
4. Celiac disease and immunosuppression.
5.
- PTLD: look for LAD, solid masses, and hepatosplenomegaly in a pt s/p organ transplant.
- Melanoma mets
- Intestinal GIST: may primarily grow as an exoenteric mass that does not result in luminal obstruction. It may also ulcerate and cavitate resulting in a cavity that communicates with the small bowel lumen mimicking aneursymal dilatation seen in lymphoma.
1. What is Peutz Jegher syndrome? If multiple polyps are seen in the small bowel of a young pt, what is the likely dx?
2. What is the morphology of the polyps associated with Peutz Jegher syndrome?
3. Why is cramping a common clinical complaint?
4. What is the most common site of polyps in PJS?
5. What is the nature of the polyps in the stomach, small bowel, and colon?
1. Peutz Jegher syndrome is a disease of mucocutaneous pigmentation and GI polyposis. PJS.
2. These hamartomatous polyps have a cauliflower shape and are most commonly located in the small bowel.
3. Cramping is often due to transient intussusceptions w/n small bowel.
4. GI polyps in PJS are most commonly found in the small bowel (95%), but they can also be identified in the colon and stomach.
5. Polyps in the stomach and small bowel are hamartomatous, whereas colonic polyps are adenomatous.
1. What are the imaging features of small bowel hemangioma?
2. What syndromes are associated with increased incidence of small bowel hemangiomas?
3. What are some characteristics of diffuse hemangiomatosis?
1. Small bowel hemangioma presents as a small submucoal mass that may have calcified phleboliths.
2. Turner syndrome, Tuberous sclerosis, Blue rubber bleb nevus syndrome, and Osler Weber Rendu.
3. Rare cause of GI bleeding. Can diffusely involve the intestinal wall and can extend into the mesentery, retroperitoneum, and other adjacent tissues.
1. What is the most common location of a duplication cyst?
2. What are the complications of duplication cyst?
1. Most common location of a duplication cyst is the terminal ileum. The distal esophagus is the second most common location.
2. Duplication cysts rarely communicate with the bowel lumen. However, they can lead to compression of the bowel and can be the lead point of intussusception.
1. What are the causes of aneurysmal dilation of the bowel?
INTESTINAL LYMPHOMA:
- classic etiology of aneurysmal dilation
- destroys the wall of the small bowel forming a cavity that is in communication with the adjacent bowel lumen.
- danger of free perforation into the peritoneal cavity if the tumor is treated with chemo- or radiation therapy.
GIST:
- can also cause a mass with aneurysmal dilation of the bowel lumen.
- GIST is more common in the stomach and duodenum.
INTESTINAL METASTASES
- Melanoma is the most common intestinal metastasis to result in aneurysmal dilation.
- Obstruction and intussusception are more common manifestations.
Closed loop obstruction
A closed loop obstruction is seen as a cluster of dilated, FLUID distended segments of bowel (no air), often with mesenteric edema and engorged, obstructed vessels.
What is the ddx of smal bowel wall thickening?
CROHN DISEASE:
- segmental with skip lesions
- submucosal attenuation is edema in acute cases and fat density in chronic cases.
- marked mucosal enhancement in sites of active inflammation
- mesenteric hyperemia, fibrofatty proliferation, and lymphadenopathy.

INTESTINAL (ANGIONEUROTIC) EDEMA:
- usually segmental
- can be hereditary or associated with medications (e.g., angiotensin-converting enzyme (ACE) inhibitors), hepatitis, etc.
- submucosal attenuation is edema (water density).
- associated findings include ascites.

SMALL VESSEL VASCULITIS:
- segmental small bowel wall thickening (may be edema or hemorrhage)
- often with associated skin or other visceral lesions
- Henoch-Schönlein purpura, lupus, polyarteritis, Sjögren

INTRAMURAL SB HEMATOMA:
- can be caused by trauma or anticoagulation.
- higher density submucosal thickening is characteristic.

OPPORTUNISTIC INFECTIONS:
- common in patients with acquired immunodeficiency syndrome (AIDS) and other immune compromised conditions.
- can be caused by viruses (e.g., cytomegalovirus (CMV)), protozoa (Giardia, Cryptosporidium), and Mycobacterium (MAI).
- Giardiasis can occur in immune competent hosts and favors proximal small bowel (SB); common cause of traveler's diarrhea.
- for Mycobacterial infection, look for caseated (low density) mesenteric nodes.

GVHD
WHIPPLE DISEASE
- systemic bacterial infection (Tropheryma whippelii)
- nodes have high fat content and low density (0-20 HU)

METS/LYMPHOMA

VASCULAR:
- Arterial/venous thrombosis: Acute arterial mesenteric ischemia is characterized by focal ileus and diminished or absent mucosal enhancement. Mesenteric infiltration and vascular engorgement are seen more often in venous thrombosis
SHOCK BOWEL
- characteristically diffuse with marked thickening.
- attenuation is of water density.
- intense mucosal enhancement
- associated findings include mesenteric and peripancreatic edema.
- intense enhancement of solid organs.
- This may occur after visceral and/or cerebral traumatic injuries.
What is a complication of cystic fibrosis seen in the small bowel?
Distal intestinal obstructive syndrome (DIOS) = dilated, feces-filled distal small bowel.
small bowel fold thickening
1. Normal small bowel fold density is > 5 folds per inch in the jejunum and 2-4 folds per inch in the ileum.
2. Small ball fold thickening can be grouped into localized (segmental) versus diffuse. it can be further divided to irregular/nodular versus straight.
3. Diffuse thickening of the small bowel folds may be due to an AI infection, Whipple disease, lymphoma, lymphangiectasia, hypoproteinemia, amyloidosis, or mastocytosis.
4. localized thickening of the small bowel may be caused by neoplasm, ischemia, hemorrhage, Crohn disease, or infection. note: Cryptosporidium and Giardia affect the proximal small bowel and jejunu, and TB affects the TI.
5. nodular folds may be due to eosinophilic gastroenteritis, amyloidosis, MAI infection, Whipple disease, lymphangiectasia, or lymphoma.
6. adenopathy may be associated with MAI infection, Whipple disease, lymphoma, Crohn disease, or amyloidosis.
Small bowel dilatation
SMALL BOWEL OBSTRUCTION
ADYNAMIC ILEUS
CELIAC SPRUE
SCLERODERMA
Celiac sprue
- 2/2 hypersensitivity to gluten resulting in damage to the mucosal lining of the small intestine.
- results in hypersecretion of fluid and malabsorption.
- **Small bowel dilation, reversal of jejunal and ileal fold patterns, dilution of barium due to hypersecretion.
- Transient intussusceptions are common.
- Increased risk for development of malignancies including lymphoma and adenocarcinoma.