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MD3002 GI/GU/Renal > Tumours of Lower GIT > Flashcards

Tumours of Lower GIT Flashcards

1
Q

Where are adenomas commonly found in the small intestines and its appearance?

A

ampulla of Vater (looks enlarged with a velvety surface)

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2
Q

Where are adenocarcinomas commonly found in the small intestines, what type of mass are they and their appearance?

A
  • duodenum
  • polypoid exophytic mass
    (napkin-ring encircling pattern)
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3
Q

Describe non-neoplastic and neoplastic tumours in the colon and rectum

A
  • non-neoplastic can be hyperplastic or hamartomatous

- neoplastic adenomas can be tubular (most common), villous or tubulovillous

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4
Q

Where are hyperplastic polyps usually found and what do they look like?

A
  • rectosigmoid colon

- look like nipple-like, hemispheric, smooth, moist, protrusions of the mucosa

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5
Q

Describe the histology of the hyperplastic polyps

A
  • well-formed glands and crypts
  • lined with non-neoplastic epithelial cells
  • most show differentiation into mature goblet or absorptive cells
  • no malignant potential
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6
Q

Describe hamartomatous polyps

A
  • juvenile polyps (usually affects children under 5)
  • found in rectum usually
  • are malformations of the mucosal epithelium in lamina propria
  • Peutz-Jeghers polyps (genetic syndrome)
  • stomach, colon or small bowel
  • involve mucosal epithelium, lamina propria and muscularis mucosa
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7
Q

Describe the histology of hamartomatous polyps (juvenile polyps)

A
  • abdundant cystically dilated glands
  • inflammation
  • surface can be congested or ulcerated
  • no malignant potential
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8
Q

Describe the histology of hamartomatous polyps (Peutz-Jeghers polyps)

A
  • large and pedunculated

- no malignant potential but increased risk of pancreas/breast/lung/ovary/uterus carcinoma

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9
Q

Neoplastic adenomas can be precursors for cancer, how is risk correlated?

A
  • polyp size:
  • rare if tubular adenoma less than 1cm
  • high risk if sessile villous adenoma greater than 4cm
  • histological architecture
  • severity of epithelial dysplasia
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10
Q

Describe the location and morphology of tubular adenomas

A
  • mostly found in colon
  • usually less than 2.5cm
  • smaller ones tend to be smooth-contoured and sessile
  • larger ones tend to be coarsely tubulated and have slender stalks raspberry like
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11
Q

Describe the histology of tubular adenomas

A
  • salk of fibromuscular tissue and prominent blood vessels
  • low-grade dyspalstic epithelium that lines glands as tall hyperchromatic, disordered epithelium
  • can contain mcin vacuoles
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12
Q

Describe the location and morphology of villous adenomas

A
  • mostly rectum and rectosigmoid
  • sessile and can be up to 10cm
  • velvety or cauliflower like masses
  • can project up to 3cm above normal mucosa
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13
Q

Describe the histology of villous adenomas

A
  • villiform extensions of mucosa

- covered in dysplastic, disordered columnar epithelium

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14
Q

What are the 3 things that signify an adequate removal of pedunculated adenoma (stalked)?

A
  • adenocrcinoma is superficial and does not approach margin of excision across base of stalk
  • no vascular or lymphatic invasion
  • carcinoma not poorly differentiated
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15
Q

What kind of polyps do patients with FAP syndrome tend to develop?

A

tubular adenomas

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16
Q

What are the dietary risk factors of colorectal cancer?

A
  • excess caloric intake relative to requirements
  • low content vegetable fibre
  • high content refined carbohydrates
  • intake of red meat
  • decreased intake of protective micronutrients
17
Q

What are the most common sites of colorectal adenocarcinomas?

A
  • rectosigmoid colon (55%)
  • caecum/ascending colon (22%)
  • transverse colon (11%)
  • descending colon (6%)
  • other sites (6%)
18
Q

Describe the morphology of tumours found in the proximal colon

A
  • polypoid, exophytic masses
  • obstruction uncommon
  • penetrates bowel wall as subserosal and serosal white, firm masses
19
Q

Describe the morphology of tumours found in the distal colon

A
  • annular, encircling lesions
  • margins heaped up, beaded and firm
  • mid region is ulcerated
  • lumen narrowed
  • possible distension of proximal bowel
  • penetrates the bowel as subserosal and serosal white firm masses
20
Q

Describe the histology of colorectal adenocarcinomas

A
  • can range from tall columnar cells resembling the adenomatous lesion counterpart
  • to undifferentiated, anaplastic (poorly differentiated) masses
  • may produce mucin
  • invasive tumour incites srtong desmoplastic stromal response (adhesions or fibrous connective tissue within a tumour)
21
Q

Describe the clinical symptoms of colorectal cancer

A

If caecum and right colonic:

  • fatigue
  • weakness
  • iron-deficiency anaemia

If left sided lesion:

  • occult bleeding
  • changes in bowel habit
  • crampy left lower quadrant discomfort
22
Q

Describe Dukes’ Staging of colorectal cancer

A

A) confined to submucosa or muscle layer
B) spread through the muscle layer but no involvement of lymph nodes yet
C) involvement of lymph nodes

23
Q

What are carcinoid tumours?

A

tumours derived from endocrine cells

24
Q

What factors determine the aggression of carcinoid tumours?

A
  • site of origin
  • depth of local penetration
  • size of tumour
  • histological features of necrosis and mitosis
25
Q

Describe the morphology and location of carcinoid tumours

A
  • usually solitary lesion
  • mostly found in appendix (or small intestine, rectum etc)
  • intramural or submucosal masses that create small polypoid or plateau-like elevations
  • colid, yellow-tan appearance on transection
26
Q

Describe the histology of carcinoid tumours

A
  • neoplastic cells may form discrete islands, trabecular, stands, glands or undifferentiated sheets
  • tumour cells uniformly similar
  • scant pink granular cytoplasm, and round to oval stippled nucleus
27
Q

Describe carcinoid syndrome

A
  • cutanous flushes
  • apparent cyanosis
  • diarrhoea, cramps, nausea, vomiting
  • cough, wheeze, dyspnoea
28
Q

What are the GI lymphomas?

A

B-cell lymphomas:

  • MALT (in stomach, small intestine, proximal colon and distal colon)
  • immunoproliferative small intestinal disease

T-cell lymphomas:

  • associated with long-standing malabsorption syndrome
  • poor prognosis
29
Q

Describe mesenchymal tumours

A
  • lipomas (firm nodules arising within submucosa or muscularis propria)
  • leiomyomas
  • leiomyosarcomas (large, bulky intramural masses that fungate and ulcerate into lumen or project subserosally into abdo space)
30
Q

Describe tumours of the anal canal

A
  • warts commonest benign neoplasm

Carcinomas:

  • basoloid pattern (immature proliferative cells derived from basal layer of stratified squamous epithelium)
  • squamous cell carcinoma (closely associated with chronic HPV infection)
  • adenocarcinoma (extension of rectal adenocarcinoma)
  • malignant melanoma

MD3002 GI/GU/Renal (64 decks)

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