Colon Flashcards
Ahaustral and diffusely granular appearing mucosa
UC
What are the critical radiographic findings for UC
Granular or stippled appearance of involved mucosa
Continuous colon involvement
Circumferential bowel wall symmetry
What are the extraintestinal manifestations of UC
Erythema nodosum, pyoderma gangrenosum, PSC, cholangiocarcinoma, arthritis, sacroilitis, spondylitis, iritis
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
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!
What is the most common presentation of IBD on CT
Bowel wall thickening with wall enhancement w/wo polypoid filling defects
What suggests active IBD
Hyperenhancement of bowel wall and vascular engorgement
What is the healing pattern in UC?
Same as inflammation, begins in rectum and progresses proximally
How long after dx until theres an increased risks for CRC in UC?
10 years
T or F - the clinical activity of UC has a correlation with cancer risk
False
What are the possible presentations of CRC in UC?
Annular constricting lesions
Flat, infiltrating tumors
Strictures (25%)
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
Which comes first in UC - spondylitis or IBD
spondylitis
Differentiatie pseudomembranous colitis and UC
Pseudomembranous colitis has thicker colonic wall with preserved but thickened haustrations.
Fatty attenuation in a thickened colon wall suggests what
Inactive IBD
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
What is the difference between strictures in UC and crohns?
Crohns strictures do not have the same malignant potential
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
What is the earliest sign of diverticulitis
Fat stranding surrounding the colon
What is the size cutoff for ABx in diverticulitis abscess
Differentiate crohns from colitis in the setting of an intramural fluid collection
Crohns will have ulcerated mucosa, diverticulitis will have normal mucosa
What is a phlegmon
Diffuse inflammation of the soft tissues due to infection
What is the normal diameter and wall thickness of the appendix
Normal diameter - 6mm
Wall - 2mm
What are the three categories of appendiceal abscess?
Phlegmon - abx
Well defined abscess - percutaneous drainage
Poorly defined multicompartmentalized abscess - operation
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?
5%
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
