Colon Flashcards by Alex Grushky

Ahaustral and diffusely granular appearing mucosa

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What are the critical radiographic findings for UC

Granular or stippled appearance of involved mucosa

Continuous colon involvement

Circumferential bowel wall symmetry

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What are the extraintestinal manifestations of UC

Erythema nodosum, pyoderma gangrenosum, PSC, cholangiocarcinoma, arthritis, sacroilitis, spondylitis, iritis

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What are the two polypoid changes that can develop in UC?

Which one occurs in milder disease

1) Pseudopolyps - islands of normal colonic mucosa surrounded by denuded ulcerative mucosa
2) Inflammatory polyps - inflamed/elevated mucosa surrounded by granular mucosa, usually in patients with less severe disease

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What is toxic megacolon?

What is the risk?

Complication with UC/crohns

Dilation (>6cm) and adynamic ileus due to inflammatory changes in the muscular layers and serosa. Can have PSEUDOPOLYPS as well

Perforation!

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What is the most common presentation of IBD on CT

Bowel wall thickening with wall enhancement w/wo polypoid filling defects

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What suggests active IBD

Hyperenhancement of bowel wall and vascular engorgement

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What is the healing pattern in UC?

Same as inflammation, begins in rectum and progresses proximally

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How long after dx until theres an increased risks for CRC in UC?

10 years

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T or F - the clinical activity of UC has a correlation with cancer risk

False

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What are the possible presentations of CRC in UC?

Annular constricting lesions
Flat, infiltrating tumors
Strictures (25%)

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How does chronic UC appear on BE?

Colon devoid of normal haustral markings and a diffusely shortened and often narrowed colonic lumen. FEATURELESS and RIGID

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Which comes first in UC - spondylitis or IBD

spondylitis

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Differentiatie pseudomembranous colitis and UC

Pseudomembranous colitis has thicker colonic wall with preserved but thickened haustrations.

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Fatty attenuation in a thickened colon wall suggests what

Inactive IBD

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What is the earliest change in crohns colitis and how does it present radiographically?

Submucosal granulomatous inflammation

Enlarged lymphoid follicles with poorly defined borders and small central umbilication

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What is the difference between strictures in UC and crohns?

Crohns strictures do not have the same malignant potential

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UC vs Crohns

Higher risk of cancer
Granular vs aphthous ulcer
Symmetric or asymmetric?

UC - higher risk of cancer, granular mucosa, symmetric

Crohns - aphthous ulcer, asymmetric

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What is the earliest sign of diverticulitis

Fat stranding surrounding the colon

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What is the size cutoff for ABx in diverticulitis abscess

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Differentiate crohns from colitis in the setting of an intramural fluid collection

Crohns will have ulcerated mucosa, diverticulitis will have normal mucosa

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What is a phlegmon

Diffuse inflammation of the soft tissues due to infection

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What is the normal diameter and wall thickness of the appendix

Normal diameter - 6mm

Wall - 2mm

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What are the three categories of appendiceal abscess?

Phlegmon - abx
Well defined abscess - percutaneous drainage
Poorly defined multicompartmentalized abscess - operation

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Where is the most common place for bowel ischemia

Splenic flexure

What are the 3 events that occur in bowel ischemia?

1) mucosal sloughing w/wo collateral blood flow or reconstitution 2) deeper ischemia resulting in stricture formation 3) Severe ischemia resulting in transmural necrosis/perforation

What are the findings of an ischemic bowel?

Adynamic ileus Pneumatosis Pneumoperitoneum Thickened haustral folds (thumbprinting)

What is the usual dose for radiation enteritis? What is the underlying path?

45 Gy Occlusive endarteritis

When do radiation induced strictures usually occur?

2 years

What is the appearance of acute radiation enteritis? Chronic?

Acute - shaggy apperance with wall thickening and luminal narrowing Chronic - absent haustral folds with stricture

Diffusely thickened haustral folds DDx - differentiate them

Pseudomembranous colitis - abx use IBD - occasional polyps, can be segmental Ischemic - segmental Neutropenic - history

Tx pseudomembranous colitis?

Vancomycin

What part of gi system do chemo drugs affect most often?

Cecum or right colon - direct effect

What is the life cycle of entamoeba histolytica

Ingestion of amebic cyst Shedding of inner capsule and trophozoite release in alkaline small bowel Burrow into intestinal wall and cause ulceration Secondary bacterial infection

Where does amebiasis most commonly affect bowel

Cecum and sigmoid

How does amebiasis present on imaging?

Wall thickening and ulcerations, usually in the cecum

What is the colon cutoff sign? What is it seen in?

Gaseous distention of right and transverse colon with little gas seen beyond splenic flexure due to pancreatic mass effect due to inflammation

Where is a pancreatic effusion most commonly seen

Left anterior pararenal space and lesser sac

Where do fistualas form in pancreatitis

Splenic flexure

What is the pathology behind bowel scleroderma

Patchy replacement of muscular layers of colon with collagen and elastic fibers Intimal proliferation of feeding arteries with possible ischemia occurs

How does scleroderma present radiographically?

ANTIMESENTERIC border develops sacculations or pseudodiverticula due to limb supporting tissues. Mesenteric side is spared because tissues and vessels in this regions support bowel wall Haustral loss, redundancy, narrowing (secondary to ischemia)

Main DDx for wide mouth sacculations and asymmetric wall involvement?

Scleroderma - antimesenteric Crohns - segmental, mesenteric or antimesenteric

Fold thickening with skeletal sclerosis

Mastocytosis

Most common site for epiploic appendigitis? Differentiate between diverticulitis

Sigmoid Lack of bowel wall thickening and epicenter located away from bowel wall

What are the three types of bowel polyps?

Adenomatous Hyperplastic Hamartomatous

What are the three subtypes of adenomatous polyp

Tubular Tubulovillous Villous

Which adenomatous polyp has worst potential?

Villous

Risk of malignancy in colonic polyps is proportional to size T or F

T, greatest if >2cm

On barium enema, how does a villous adenoma present assuming it is larger than 2cm

Barium will fill interstices within a soft and compressible mass

What is a flat polyp? What is their significance

Polyp that is 2x wide as they are tall and not more than 3mm above flush surface Higher risk of cancer

Why do patients with peutz-jeghers get cramping?

Transient intussuceptions

What is the difference between polyps in the SB vs colon in peutz-jeghers?

SB is more common (95%) and usually hamartomatous Colon is rare and usually adenomatous

What are the extraintestinal manifestations of gardner syndrome

Sebaceous cysts Benign mesencyhymal tumors (lipoma, fibroma) Malignant mesenchymal tumors Fibrous tissue proliferation (Desmoids, keloids) Dense bone formation

What are the extraintestinal manifestations of Turcot syndrome

CNS tumors, thyroid tumors

What are the extraintestinal manifestations of Lynch syndrome?

Endometrial and ovarian tumors

What are the extraintestinal manifestations of peutz-jeghers syndrome?

Mucocutaneous pigmentation | Breast/ovary/endometrium/pancreatic cancer

What are the extraintestinal manifestations of Cronkhite-Canada syndrome?

Alopecia, onychodystrophy, hyperpigmentation

What are the extraintestinal manifestations of Cowden syndrome?

Malignancies of breast and thyroid | Lhermitte duclos

Most frequent submucosal tumor of colon? Changeable shape

Lipoma

Colonic filling defect with very smooth surface suggest what location?

Submucosal

Characteristic features of coloinc lipoma?

Smooth surface and changeable shape

Where, in the colon, do GISTS form

Rectum

Mass at base of cecum T1 hypo T2 hyper +CE

Appendiceal carcinoid/adeno

What percentage of patients have multifocal colon cancer?

Mesenteric fat and vessels within a colonic mass are pathognomonic for what?

Intussuception

What are the 4 layers of bowel from inside to outside

Mucosa Submucosa Muscularis propria Serosa

What two key findings need to be reported for rectal cancer in MRI?

T stage and distance from mesorectal fascia

What is the T staging for rectal cancer

T1 - invades submucosa T2 - invades muscularis propria T3 - Penetrates the muscularis propria and extends into perirectal tissues (mesorectum) T4 - Directly invades other organs/structures

What is the defining feature deciding between radiation and surgery in rectal cancer

Tumor involvement

What is key to rule out when suspecting perforated diverticulitis?

Perforated colon cancer

What is the recurrence rate for colon cancer following resection

30-50% in 2 years

Which primary tumors affect the following aspects of colon: Anterior wall of rectum, inferior sigmoid Anterior rectum only Large intraluminal nonobstructing polypoid mass Transverse colon via gastrocolic and transverse mesocolon Inferior transverse Superior transverse

``` Pelvic Prostate Renal Pancreatic/Gastric Pancreatic Gastric ```

Where are the 4 common sites of peritoneal seeding

Pouch of douglas Ileocolic region Superior aspect of sigmoid Right paracolic gutter

Where does colonic lymphoma usually present?

Cecum and rectum

Why does colonic lymphoma have a propensity to perforate?

Lack of usual desmoplastic response

Multiple round submucosal cyst like filling defects in the rectum

Colitis cystica profunda

Association with colitis cystica profunda

Pellagra | Celiac disease

DDx for multiple submucosal filling defects in rectum

Colitis cystica profunda Lymphoma - LN and usually more diffuse UC - usually more extensive

Filiform polyps with normal mucosal background?

Postinflammatory polyps

On BE, differentiate pseudopolyp from polyp

Psuedopolyp will have ring of barium surrounding it

UNIFORMLY distributed and small

Follicular lymphoid hyperplasia

Main DDx for multiple small filling defects with umbilication in colon

Follilcular lymphoid hyperplasia and Crohns

Smooth filling defect at base of cecum on BE CT shows thin walled cystic and tubular structure with mural calcification

Appendiceal mucocele

Rounded and grapelike collections of gas within the bowel wall

Pneumatosis cystoides coli

What are the causes of pneumatosis

``` Ischemia Steroids Collagen vascular disease Biopsy/interventional COPD ```

What is a dolichosigmoid?

Redundant sigmoid loop, risk for volvulus

Differentiate sigmoid and cecal volvulus

Sigmoid will twist upon an epicenter in the LLQ, with the apex of the closed loop in the RUQ, will have dilated proximal colon Cecal will twist in the RLQ, with the apex ranging anywhere from LUQ to LLQ to pelvis, will not have any dilated colon Follow the dilated loops, they will point to the origin!

What are two signs of midgut malrotation?

Jejunum in RUQ SMA to right of SMV

What is an adynamic ileus?

Atony and dilation of a portion of the colon

What is the major risk factor in cecal ileus for perforation?

Time (2-3 days)

What are the associations with rectal prolapse

Uterine/Bladder prolapse | Cystocele

What is an enterocele?

Herniation of peritoneal sac along ventral rectal wall into cul-de-sac

Inability to relax puborectalis muscle on defacating proctogram

Spastic pelvic floor syndrome

Lack of haustrations, shortening and luminal constrictions on right sided colon mainly

Cathartic colon

Key differentiating feature of cathartic colon vs UC

Wall remains distensible with normal size and contour of distal colon UC will have lack of distensibility and narrowing

Hyperlucent pelvis on plain film Narrowed and less distensible rectum on BE fatty widening of presacral space with TEARDROP shape of the bladder

Pelvis lipomatosis