Lower GI pathology

Question 1

What is Hirschsprung’s disease and what are the symptoms

Answer 1

Absence of ganglion cells in myenteric plexus

Constipation, abdominal distension, vomiting, ‘overflow’ diarrhoea

Question 2

Diagnosis and treatment of Hirschprungs disease

Answer 2

clinical impression
biopsy of affected segment.
hypertrophied nerve fibers but no ganglia.

Treatment: resection of affected

Question 3

What is Volvulus and its symptoms

Answer 3

Complete twisting of a loop of bowel at mesenteric base, around vascular pedicle
intestinal obstruction +/- infarction

small bowel (infants)
sigmoid colon (elderly)

Question 4

Complications of diverticular disease

Answer 4

Pain
Diverticulitis
Gross perforation
Fistula (bowel, bladder, vagina)
Obstruction

Question 5

Causes of acute and chronic colitis

Answer 5

Acute colitis
Infection (bacterial, viral, protozoal etc.)
Drug/toxin (esp.antibiotic)
Chemotherapy
Radiation

Chronic colitis
Crohn’s
Ulcerative colitis
TB

Question 6

Effects of colon infection

Answer 6

Secretory diarrhoea (toxin)
Exudative diarrhoea (invasion and mucosal damage)
Severe tissue damage + perforation
Systemic illness

Question 7

Pseudomembranous colitis

Answer 7

Pseudomembranous colitis refers to swelling or inflammation of the large intestine (colon) due to an overgrowth of Clostridioides difficile (C difficile) bacteria.

Question 8

Diagnosis and treatment of pseudomembranous colitis

Answer 8

Histology: Characteristic microscopic features on biopsy
Laboratory: C. difficile toxin stool assay

Therapy: Metronidazole or Vancomycin

Question 9

Where does ischaemic colitis occur

Answer 9

Usually occurs in segments in “watershed” zones, e.g. splenic flexure (SMA and IMA) and the rectosigmoid (IMA and internal iliac artery)

Question 10

Features of Crohns disease

Answer 10

Whole of GI tract can be affected (mouth to anus)
‘Skip lesions’
Transmural inflammation
Non-caseating granulomas
Sinus/fistula formation

Question 11

Histology of Crohns

Answer 11

‘Fat wrapping’
Thick ‘rubber-hose’ like wall
Narrow lumen
‘cobblestone mucosa’

Question 12

Crohn’s disease: extra-intestinal

Answer 12

Arthritis
Uveitis
Stomatitis/cheilitis
Skin lesions
Pyoderma gangrenosum- ulcers on leg 
Erythema multiforme- target lesions 
Erythema nodosum- tender red bumps on skin

Question 13

Ulcerative colitis features

Answer 13

Involves rectum and colon in contiguous fashion.
May see mild ‘backwash ileitis’ and appendiceal involvement but small bowel and proximal GI tract not affected.
Inflammation confined to mucosa

Question 14

Complications of UC

Answer 14

Severe haemorrhage
Toxic megacolon
Adenocarcinoma (20-30 x risk)

Question 15

Ulcerative colitis: extraintestinal

Answer 15

Arthritis 
Myositis- muscles 
Uveitis/iritis
Erythema nodosum, pyoderma gangrenosum
Primary Sclerosing Cholangitis (5.5% in pancolitis)

Question 16

Types of colonic/rectal adenomas

Answer 16

Tubular
Villous
Tubulovillous

Question 17

Symptoms of adenomas

Answer 17

Usually none

Bleeding/anaemia

Question 18

Risk factors for cancer

Answer 18

Size of polyp (> 4 cm approx 45% have invasive malignancy)
Proportion of villous component
Degree of dysplastic change within polyp

Question 19

Familial Adenomatous polyposis (FAP/APC)

Answer 19

Autosomal dominant - average onset is 25 years old

APC tumour suppressor gene

Adenomatous polyps, mostly colorectal

Question 20

Gardner’s Syndrome

Answer 20

Same clinical, pathological, and etiologic features as FAP, with high Ca risk

Distinctive extra-intestinal manifestations:
multiple osteomas of skull & mandible
epidermoid cysts
desmoid tumors

Question 21

Hereditary Non-polyposis Colorectal Cancer (HNPCC)

Answer 21

Uncommon autosomal dominant disease

Numerous DNA replication errors (RER)

Onset of colorectal cancer at an early age
High frequency of carcinomas proximal to splenic flexure
Poorly differentiated and mucinous carcinoma more frequent

Presence of extracolonic cancers

Question 22

Colorectal carcinoma type and symptoms

Answer 22

98% are adenocarcinoma

Bleeding
Change of bowel habit
Anaemia
Weight loss
Pain
Fistula

Question 23

Staging of colon carcinomas

Answer 23

Dukes’ staging
A = confined to wall of bowel
B = through wall of bowel
C = lymph node metastases
D = distant metastases