Histopathology 16: Lower GI

Question 1

A 2 year old boy with down syndrome presents with symptoms of constipation with overflow diarrhoea and vomiting. There are signs of abdominal distension. Didnt pass meconium in first 24h of life

What is the most likely diagnosis ?

Answer 1

Hirschsprung’s disease - most common congenital GI abnormality

Question 2

Where does Volvulus tend to occur in children? Where does it occur in adults ?

Answer 2

Children= small bowel 
Adults = Sigmoid colon

Question 3

Which organism causes pseudomembranous colitis ? diagnosis?

Answer 3

C.difficile = antibiotics kill commensal bacteria and allow C.diff to flourish. It’s endotoxins cause Pseudomembranous colitis

TOXIN STOOL ASSAY

Question 4

List 5 features of Crohn’s disease ?

Answer 4

Transmural inflammation 
Skip lesions 
Non-caseating granulomas 
Cobblestone mucosa 
Can affect anus to mouth

Question 5

List 5 features of Ulcerative colitis ?

Answer 5

Involves rectum and Colon but not small bowel
Inflammation confined to the mucosa
Inflammation is continuous, no skip lesions
Backwash ileitis- terminal ileum gets involved
Can cause toxic megacolon

Question 6

List 3 skin lesions seen in Crohn’s ?

Answer 6

Erythema multiforme
Erythema nodosum
Pyoderma gangrenosum

Question 7

List 3 familial syndromes characterised by polyps ?

Answer 7

Familial adenomatous polyposis
Peutz-jeghers syndrome
Hereditary non polyposis colorectal cancer (HNPCC)

Question 8

Name 2 subtypes of FAP ?

Answer 8

Gardner’s syndrome

Turcot syndrome

Question 9

List 5 extra-intestinal manifestations of Gardner’s syndrome ?

Answer 9

Multiple Osteomas of the skull and mandible
Epidermal cysts
Desmoid tumours
Dental carries/ unerrupted supernumerary teeth
Post surgical mesenteric fibromatoses

Question 10

List 3 features seen in carcinoid syndrome ?

Answer 10

• Flushing
• Diarrhoea
• Bronchoconstriction / tachycardia

Question 11

Which test is used to diagnose carcinoid syndrome ?

Answer 11

24 hour urine 5-HIAA

Question 12

Which paediatric disease presents with up to 100 hamartomatous polyps in children <5 years old ?

Answer 12

Juvenile polyposis

Question 13

List 3 features of peutz-jeghers syndrome ?

Answer 13

• multiple hamartomatous polyps
• freckles around mouth
• mucocutaenous hyperpigmentation

Question 14

Which staging system is used to stage colorectal cancer ? describe the stages?

Answer 14

Duke’s staging

A - confined to mucosa

B1 - Extends to muscularis propia
B2 - Transmural invasion

B1 - Extends to muscularis propia + LN INVOLVEMENT
B2 - Transmural invasion + LN INVOLVEMENT

D = Distant Mets

Question 15

Which tumour marker identifies colorectal cancer ?

Answer 15

CEA

Question 16

Where does ischaemic colitis occur usually?

Answer 16

watershed zones - supplied by 2 vessels

Splenic flexure + rectosigmoid areas

Question 17

What are the complications associated w/ UC?

Answer 17

Toxic megacolon

20-30x risk of adenocarcinoma

Question 18

What are some extra-intestinal manifestations of IBD?

Answer 18

Arthritis
Uveitis
Stomatitis/ chelitis
Pyoderma gangrenosum
Erythema nodosum

Question 19

What are the different polyp types?

Answer 19

Polyps = benign dysplastic lesions that are often precursors to adenocarcinomas

tubular
tubulovillous
villous - greatest risk of malignant transformation

Question 20

What factors determine the risk of malignant transformation in a polyp?

Answer 20

Polyp type - villous (greatest risk)

Polyp size

Polyp degree of dysplasia

Question 21

What are colorectal cancers, how common in UK?

Answer 21

98% = adenocarcinomas

2nd most common cancer death in UK

Question 22

RFs for colorectal cancer?

Answer 22

Low fibre, high fat diet, no exercise, obesity, chronic IBD

Question 23

What are the inherited lower GI conditions that increase risk of colorectal cancer? inheritance? mx?

Answer 23

FAP

Gardeners syndrome

Hereditary Non-polyposis Colorectal Cancer / Lynch Syndrome

inheritance = AD

mx = MONITORING + TOTAL COLECTOMY

Question 24

What are the main features of FAP?

Answer 24

Lots of polyps - ~1000

APC tumour suppressor geneonchromosome 5q21

100% will have cancer within 10-15 years

Question 25

What are the main features of gardeners syndrome?

Answer 25

Subtype of FAP with extra-intestinal manifestations:

Osteomas of the skull and mandible, epidermoid cysts, desmoid tumours, dental caries, unerupted supernumerary teeth

NB QUESTIONS MAY DESCRIBE POOR DENTITION

Question 26

What are the main features of Hereditary Non-polyposis Colorectal Cancer / Lynch Syndrome (AD)?

Answer 26

Defective DNA mismatch repair

Another extra-colonic cancer at the same time – endometrium, breast, prostate, stomach

Question 27

VSA1: A 20 year old man was admitted following a 6 day history of diarrhoea, abdominal pain and weight loss. A colon biopsy revealed granulomata.

What is the most likely diagnosis?

Answer 27

Crohn’s Disease

No non-caseating granulomas in ulcerative colitis

Question 28

VSA2: What is the diagnostic test for C. diff infection?

Answer 28

Toxin stool assay

Question 29

VSA3: Mutation in which gene is present in Familial Adenomatous Polyposis?

Answer 29

APC (Adenomatous polyposis coli) – tumour suppressor gene