Colorectal pathology Flashcards
What is a polyp?
Protrusion above an epithelial surface
Types of polyps
Epithelial or mesenchymal
Types of benign epithelial polyps
Neoplastic - adenoma, hamartomatous - juvenile polyp, Peutz-jeghers, metaplastic
Types of malignant epithelial polyps
Polypoid (adenocarcinomas), carcinoid polyps
Benign mesenchymal polyps
Lipoma, Lymphangioma, Haemangiomas, Fibromas, Leiomyoma
Malignant mesenchymal polyps
Sarcoma, lymphotamous
Why must all adenomas be removed?
They are dysplastic - pre-malignant
Microscopic view of adenomas
Tubulovillous structures
Which staging predicts prognosis in colorectal carcinoma?
Duke’s staging
Dukes staging (A-C)
Dukes A - confined by muscularis propria
Dukes B - through muscularis propria
Dukes C - metastatic to lymph nodes
Which side does colorectal carcinoma most commonly affect?
Left side (75%)
Presenting complaint of colorectal carcinoma which affects the left side (rectum, sigmoid, descending colon)
Blood per rectum, altered bowel habit and obstruction
Presenting complaint of colorectal carcinoma which affects the right side (caecum, ascending colon)
Anaemia or weight loss
Patterns of spread of colorectal carcinoma
Local invasion, lymphatic spread, haematogenous
Hereditary non polyposis coli:
- How many polyps?
- Autosomal dominant or recessive?
- Where is the defect?
- Which tumours does it cause?
- Which cancers is it related to?
- <100 polyps
- Autosomal dominant
- Defect in DNA mismatch repair, mutation in MLH-1, MSH-2, PMS-1 or MSH-6 genes
- Right sided tumours and mucocinos tumours
- Gastric and endometrial carcinoma
Familial adenomatous polyposis:
- How many polyps?
- Autosomal dominant or recessive?
- Where is the defect?
- Which cancers is it related to?
- > 100 polyps
- Autosomal dominant
- Tumour suppressor defect, inherited mutation in FAP gene
- Desmoid tumours and thyroid carcinoma
What is diverticular disease?
Mucosal herniation through the muscle coat
Where does diverticular disease often occur?
Sigmoid colon
What can diverticular disease be due to?
Low fibre intake
Complications of diverticular disease
- Pericolic abscess
- Perforation
- Haemorrhage
- Fistula
- Stricture
Diagnosis of diverticulosis
History and clinical examination, barium enema and sigmoidoscopy
Clinical features of diverticulitis
Left iliac fossa pain/tenderness, the patient may be septic, and there may be altered bowel habit
Which classification is used for diverticulitis
Hinchey classification
Hinchey classification
- Stage 0 – clinically mild diverticulitis
- Stage Ia – confined pericolic diverticulitis (beside the colon)
- Stage Ib – abscess formation (<5cm) in the proximity of the primary inflammatory response
- Stage II – intra-abdominal abscess, pelvic or retroperitoneal abscess, abscess distant from the primary inflammatory process
- Stage III – generalised purulent peritonitis
- Stage IV – faecal peritonitis
Treatment for uncomplicated diverticulitis
Antibiotics
Treatment for complicated diverticulitis
Percutaneous drainage, Hartmann’s procedure, laparoscopic lavage and drainage, primary resection/anastomosis
Colitis
Inflammation of the colon
Causes of colitis
- Infective colitis
- Ulcerative colitis
- Crohn’s disease
- Ischaemic colitis
Symptoms of colitis
Diarrhoea +/- blood, abdominal cramps, dehydration, sepsis, weight loss and anaemia
Diagnosis of colitis
X-ray, sigmoidoscopy + biopsy, stool cultures, barium enema
Treatment of ulcerative colitis/Crohn’s colitis
IV fluids, IV steroids, GI rest
In which patients is ischaemic colitis most common?
Elderly or arteriopaths
Colonic angiodysplasia:
- What is it?
- Diagnosis
- Management
- Small vascular malformation of the gut which can cause submucosal lakes of blood
- Angiography, colonoscopy
- Embolisation, endoscopic ablation, surgical resection
Causes of large bowel obstruction
Colorectal cancer, benign stricture, volvulus
Volvulus
When a loop of intestine twists round itself
Treatment for large bowel obstruction
Resuscitate, operate, stenting
Diagnosis of sigmoid volvulus
Plain x-ray abdomen, rectal contrast
Treatment for sigmoid volvulus
Flatus tube, surgical resection
Risk factors for colorectal cancer
- Older age
- Low intake of fibre
- High intake of fat, sugar, alcohol, red meat, processed meats
- Obesity
- Smoking
- Lack of physical exercise
Ways of presenting with colorectal cancer
Bowel screening programme, urgent - via surgical outpatient department or endoscopy, emergency (obstruction, rectal bleeding, palpable mass, perforation)
Signs and symptoms of right sided cancers
- Unexplained iron deficiency anaemia
- Persistent tiredness
- A persistent and unexplained change in bowel habit
- Unexplained weight loss
- Abdominal pain (colicky)
- Lump in the abdomen
Signs and symptoms of cancers in the left side and rectum
- Rectal bleeding
- Feeling of incomplete emptying
- Worsening constipation
Investigations for colorectal cancer
Sigmoidoscopy, colonoscopy, CT colonography
Steps in transformation of polyp to cancer
Normal epithelium (via APC mutation and COX-2 overexpression) → Hyperproliferative epithelium. Aberrant cryptic foci → Small adenoma (via K-ras mutation) → Large adenoma (via p35 mutation and loss of 18q) → Colon carcinoma
Surgery options for colorectal cancer
Right hemicolectomy, extended right hemicolectomy, transverse colectomy, sigmoid colectomy, anterior resection, APR
Right hemicolectomy
Right colon removed and ileocolic anastomosis
Extended right hemicolectomy
Right colon and part of transverse colon removed, anastomosis between parts of colon
Transverse colectomy
Transverse colon removed and anastomosis between parts of colon
Sigmoid colectomy
Part of sigmoid colon removed and anastomosis between parts of colon
Anterior resection
Part of rectum removed, remaining parts anastomosed
APR
Sigmoid colon divided, anus resected and perianal skin is closed, colonostomy
Factors influencing enhanced recovery following surgery for colorectal cancer
No premed, no NGT, no bowel prep, avoid fluid overload, prevent hypothermia, no drains, small incision, early mobilisation, early removal of catheters, NSAIDs, no opiods
Colorectal cancer treatment following surgery
Chemotherapy, radiotherapy depending on staging
Palliation for colorectal cancer
Stenting, palliative chemotherapy/radiotherapy, defunctioning, bypass
