Histo path - lower GI

Question 1

Atresia/stenosis

Normal anus but small rectum and anal canal without stool, dilated proximal bowel

Answer 1

Common in Down’s - Hirschprung’s Disease

Absence of ganglionic cells in myenteric plexus

biopsy: hypertrophied nerve fibres w/out ganglia. 
 RET pro-oncogene 

resection of affected area (frozen section)

Question 2

Partial or complete doubling of a variable length of bowel, very cystic

Answer 2

Duplications

Question 3

No anal canal, rectum ends above levator ani muscle

Answer 3

Imperforate anus

Causes severe obstruction
● Associated with anomalies in vertebrae and urinary tract, defective innervation of pelvic muscles, fistulas from rectum to bladder, urethra or vagina

Question 4

Serosa-based fibrous bands of scar tissue that cause colon to connect and adhere to nearby structures, typically other viscera

Answer 4

Adhesions

Typically due to injury, such as prior surgical procedures, infection (i.e. peritonitis), or radiation damage

Question 5

blind pouch leading off alimentary tract, lined by mucosa that communicates with gut lumen

Multiple, small, flasklike invaginations present along prominent taeniae coli, filled with mucin or stool but easily emptied, may bulge into serosa

Answer 5

Diverticula

cramping, discomfort, constipation, distention, sensation of inability to completely empty rectum; alternating constipation and diarrhea

No muscle layer around diverticula except for residual bundles of muscularis mucosa

Intramucosal ganglion cells are common

Question 6

protrusion of a viscus through the wall in which it is normally contained

Answer 6

Herniation

Question 7

Complete twisting of loop of bowel around its mesenteric base of attachment, causing obstruction and infarction

Usually involves cecum or sigmoid

Answer 7

Volvulus

Colon may be ischemic or gangrenous

Question 8

24 year old man, with bloody diarrhoea with stringy mucus with pains/cramps that are relieved on defecation.

usually limited to colon, diffuse continuous disease from rectum proximally

Affects primarily mucosa and submucosa, except in most severe cases

Answer 8

Ulcerative Colitis

Affects primarily mucosa and submucosa (shallow ulcers), except in most severe cases

Bowel wall normal thickness (not thickened) 

No granulomas, no fissures, no transmural inflammation (except in fulminant cases), no submucosal edema or inflammation, no neuronal hyperplasia

Complications: perforation, toxic megacolon, adenocarcinoma 20-30x risk, worse than Crohns

Question 9

What are some extra-abdominal complications of UC?

Answer 9

Arthritis

Uveitis/Iritis (iritis affects sight, uveitis doesn't) 

Skin lesions 

    Erythema nodosum 

    Pyoderma gangrenosum 

Primary Sclerosing Cholangitis  

    (5.5% in patients with pancolitis)

Question 10

Abdominal pain, watery or bloody diarrhea
Sudden onset, early fever, often with numerous (greater than 6) bowel movements daily

Signs of systemic illness

Answer 10

Infective colitis

Essentially Gastroenteritis

Question 11

Hx of Abx use (cipro, clari, co-am, cef)

Acute colitis with adherent inflammatory exudate (pseudomembrane) overlying sites of mucosal injury, usually after broad spectrum antibiotics

Yellow-white mucosal plaques, ‘mushroom cloud exudate’, neutrophil infiltration, ‘inflammatory slough’

Answer 11

Pseudomembraneous Colitis

Question 12

Sudden onset abdominal pain and bleeding

Vascular, DM, bowel obstruction

Splenic flexure (upper left) (SMA and IMA at risk) 

Rectosigmoid (lower middle) (IMA and internal iliac artery)

Answer 12

Ischaemic Colitis

Hallmarks of ischemic bowel are necrotizing phlebitis and thrombi formation

Thrombophlebitis morphology differs in viable bowel (lymphocytic) and ischemic bowel (necrotizing lesions)

petechial hemorrhages, edematous and fragile mucosa, segmental erythema, scattered erosion, longitudinal ulcerations, sharply defined segment of involvement

Ulceration (may be discrete or serpiginous) with possible cobblestone pattern resembling Crohn’s disease or pseudopolyps resembling ulcerative colitis

Ischemic changes may be mucosal, mural (due to hypoperfusion) or transmural (major vessels involved)

Question 13

Episodic mild diarrhea, fever, pain, weight loss

Sharply delimited and typically transmural involvement of bowel by an inflammatory process with mucosal damage, noncaseating, non-confluent, sarcoid-like granulomas (60%) in involved and non-involved bowel, fissuring (30%) deep into muscularis propria with formation of fistulas and strictures

Answer 13

Crohn’s Disease

Discontinuous, transmural granulomatous disease from oral cavity to anus, usually involves small intestine and colon

‘Cobblestone appearance’

5x Adenocarcinoma risk (UC is 30x)

Complications:
● Fibrosing strictures (common in terminal ileum), fistulas to loops of bowel, bladder, vagina, perianal skin

Question 14

Small adenomatous lesion, usually < 1 cm and pedunculated but may be sessile. However, it is still well-differentiated and circumscribed, without invasion of the stalk, and is benign. Glands are rounded - ‘test tube appearance’

Darker color than surrounding mucosa

Asymptomatic, with a bit of occult bleeding

Answer 14

Tubular Adenoma

Form after ‘first hit’ APC gene mutation

90% of GI tubular adenomas occur in colon; also stomach and small intestine
50% are single

Mostly asymptomatic so need regular surveillance if over 3.4cm 45% malignant change .

Question 15

Small adenomatous lesion, usually < 1 cm and pedunculated but may be sessile. However, it is still well-differentiated and circumscribed, without invasion of the stalk, and is benign. Round glandular look with villous projections.

Darker color than surrounding mucosa

Answer 15

Tubulovillous adenoma

Increased villous component increases risk of malignant change.

Dark colour shows dysplasia

Question 16

Soft, usually large and sessile with papillary villous projections, large base and no stalk. Long fronds of papillary / villous projections arising directly from mucosal surface.

“Like fingers”

Answer 16

Villous adenoma

More cancerous as more villi. Hypokalaemia as they leak proteins and K

Question 17

Small (< 5 mm), sessile, usually on top of mucosal folds, multiple and same color as surrounding mucosa

Answer 17

Hyperplastic polyps

90% of all polyps. Due to delayed shedding of epithelial cells

Question 18

Inflamed regenerating mucosa surrounded by ulcerated tissue; also granulation tissue overlying epithelium. Smooth hyperemic or hypervascular appearance; variable surface erosion

Answer 18

Pseudopolyp

caused by IBD

Question 19

Child <5, some rectal bleeding (maybe), lesion has red granular or glistening surface

Answer 19

Juvelile hamartomatous polyp

Up to 100 found in Juvenile Polyposis (AD) - may require colectomy to stop bleeding

Question 20

Many polyps, monocuaneous hyperpigmentation, freckles around mouth, palms and soles

Answer 20

Peutz-Jeghers syndrome (AD - LKB1)

Have increased risk of intussusception and of malignancy 􀃆 regular
surveillance of GI tract, pelvis and gonads.

Question 21

65 year old man presents with painless rectal bleeding, fatigue and weight loss. There is a palpable mass in his rectum. Histology shows invasion through muscularis propria, hyperchromatic cells and disordered architecture. Cells have ‘necrotic debris’.

Invasion

through Muscularis propria/externa.

Hyperchromatic, big nuclear: cytoplasmic ratio 

Increased mitotic activity 

Atypical mitotic forms 

Disordered architecture 

Invasion with reactive stromal changes

Answer 21

Colorectal adenocarcinoma

45% in rectum, 98% are adenocarcinoma

Right sided tumours: Fe def. anaemia, weight loss
Left sided tumours: change in bowel habit, crampy LLQ pain

Investigations: Proctoscopy, sigmoidoscopy, colonoscopy, barium enema, bloods e.g. FBC, CT/MRI
Carcinoembryonic antigen (CEA) – monitor disease

Most commonly mutated genes include APC, TP53, and KRAS

Question 22

Colorectal adenocarcinoma has invaded the muscularis propria but not externa, there is LN metastasis. What is the stage according to Duke’s criteria?

Answer 22

C1

1 = musc prop
2 = intramural
B= no LN
C = LN

A: confined to mucosa (5yr survival >95%)
B1: extending into muscularis propria (5yr survival 67%)
B2: transmural invasion, no lymph nodes involved (5yr survival 54%)
C1: extending to muscularis propria, with LN metastases (5yr survival 43%)
C2: transmural invasion, with lymph node metastases (5yr survival 23%)
D: distant metastases (5yr survival <10%)

Question 23

12 year old, has 100 adenomatous polyps

Answer 23

Familial adenomatous polyposis (FAP)

− 70% AD mutation in APC gene (C5q1), 30% AR mutation in DNA mismatch
repair genes
− Present 10-15yrs - >100 adenomatous polyps required for diagnosis, usually
100-1000s seen. ALL will 􀃆 adenocarcinoma if left untreated by 30yrs therefore
most have prophylactic colectomy.

Question 24

FAP like presentation but also has extra intestinal features such as osteoma’s and dental carries. Will have cutaneous skin involvement

Answer 24

Gardner’s Syndrome

Question 25

Autosomal genetic condition that predisposis to colorectal, endometrial and ovarian cancers

Answer 25

Hereditary non-polyposis colorectal cancer/Lynch syndrome (HNPCC)

− AD mutations in DNA mismatch repair genes
− Carcinomas usually in right colon, few polyps but fast progression to malignancy
therefore present usually <50yrs
− Associated with endometrial, ovarian, small bowel, transitional cell and stomach
carcinoma.