Lower GI pathology Flashcards
What is Hirschsprung’s disease and what are the symptoms
Absence of ganglion cells in myenteric plexus
Constipation, abdominal distension, vomiting, ‘overflow’ diarrhoea
Diagnosis and treatment of Hirschprungs disease
clinical impression
biopsy of affected segment.
hypertrophied nerve fibers but no ganglia.
Treatment: resection of affected
What is Volvulus and its symptoms
Complete twisting of a loop of bowel at mesenteric base, around vascular pedicle
intestinal obstruction +/- infarction
small bowel (infants) sigmoid colon (elderly)
Complications of diverticular disease
Pain Diverticulitis Gross perforation Fistula (bowel, bladder, vagina) Obstruction
Causes of acute and chronic colitis
Acute colitis Infection (bacterial, viral, protozoal etc.) Drug/toxin (esp.antibiotic) Chemotherapy Radiation
Chronic colitis
Crohn’s
Ulcerative colitis
TB
Effects of colon infection
Secretory diarrhoea (toxin)
Exudative diarrhoea (invasion and mucosal damage)
Severe tissue damage + perforation
Systemic illness
Pseudomembranous colitis
Pseudomembranous colitis refers to swelling or inflammation of the large intestine (colon) due to an overgrowth of Clostridioides difficile (C difficile) bacteria.
Diagnosis and treatment of pseudomembranous colitis
Histology: Characteristic microscopic features on biopsy
Laboratory: C. difficile toxin stool assay
Therapy: Metronidazole or Vancomycin
Where does ischaemic colitis occur
Usually occurs in segments in “watershed” zones, e.g. splenic flexure (SMA and IMA) and the rectosigmoid (IMA and internal iliac artery)
Features of Crohns disease
Whole of GI tract can be affected (mouth to anus) ‘Skip lesions’ Transmural inflammation Non-caseating granulomas Sinus/fistula formation
Histology of Crohns
‘Fat wrapping’
Thick ‘rubber-hose’ like wall
Narrow lumen
‘cobblestone mucosa’
Crohn’s disease: extra-intestinal
Arthritis Uveitis Stomatitis/cheilitis Skin lesions Pyoderma gangrenosum- ulcers on leg Erythema multiforme- target lesions Erythema nodosum- tender red bumps on skin
Ulcerative colitis features
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
Complications of UC
Severe haemorrhage
Toxic megacolon
Adenocarcinoma (20-30 x risk)
Ulcerative colitis: extraintestinal
Arthritis Myositis- muscles Uveitis/iritis Erythema nodosum, pyoderma gangrenosum Primary Sclerosing Cholangitis (5.5% in pancolitis)
Types of colonic/rectal adenomas
Tubular
Villous
Tubulovillous
Symptoms of adenomas
Usually none
Bleeding/anaemia
Risk factors for cancer
Size of polyp (> 4 cm approx 45% have invasive malignancy)
Proportion of villous component
Degree of dysplastic change within polyp
Familial Adenomatous polyposis (FAP/APC)
Autosomal dominant - average onset is 25 years old
APC tumour suppressor gene
Adenomatous polyps, mostly colorectal
Gardner’s Syndrome
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
Hereditary Non-polyposis Colorectal Cancer (HNPCC)
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
Colorectal carcinoma type and symptoms
98% are adenocarcinoma
Bleeding Change of bowel habit Anaemia Weight loss Pain Fistula
Staging of colon carcinomas
Dukes’ staging A = confined to wall of bowel B = through wall of bowel C = lymph node metastases D = distant metastases
