tbl 4 pathology (colic polyps and neoplasia) Flashcards
Polyps – can be divided into non-neoplastic and neoplastic polyps
- Colonic neoplasms
o Mainly ___________________
o Mesenchymal – GIST, Leiomyoma, lipoma
o Neuroendocrine neoplasms
o Lymphomas
- Location – colon, with other subtypes in the appendix and anal canal
- In contrast, adenocarcinomas are rare for small intestinal tumours, which are mainly comprised of ______________ and lymphomas
adenocarcinomas;
neuroendocrine neoplasms
Polyps – protuberant lesions occurring anywhere along the GIT, most common in rectosigmoid region
- Comprised of different types of lesions (heterogenous) with different histological subtypes
o Sessile, directly arising from the mucosa or __________, with stalk connecting to mucosa
o Benign or malignant
o Non-neoplastic or neoplastic
o Epithelial or mesenchymal – e.g. ___________ are mesenchymal
o Sporadic or syndromic – syndromic polyps are usually ____________, presenting as part of an inherited syndrome generally carrying a higher risk of malignancy progression as compared to isolated sporadic polyp
o Polyps or polyposis – polyposis involves multiple polyps as part of a polyp syndrome
pedunculated;
lipomatous polyps;
multiple;
Hyperplastic polyps – most common polyp comprising of ____ of all colonic polyps
- Most common at the left colon – especially ________________
- <5mm, typically small and sessile lesions
- Benign epithelial proliferations of mature goblet cells and absorptive cells
o _____ in the upper third of crypts
- No dysplasia and little/ or no malignant potential unless in rare hyperplastic polyposis syndromes with an increased risk of malignancy
o On histology, epithelium is normal colonic type
> 90%;
rectosigmoid area;
Serration;
Hamartomatous polyps
- Tumour-like malformation (not neoplasm) with abnormal mixture of cells and tissues native to that area
o Benign but there is an increased risk of developing cancer within a polyp, intestine or extraintestinal sites when in a syndromic setting - Thought to be due to developmental error but now partially attributed to germline or acquired mutations
- Can occur at many sites along GI tract as rare lesions at the stomach, small and large intestine
- Sporadic or syndromic – syndromic polyps have malignancy potential just like adenomas
Juvenile polyps – retention polyps
- Polypoidal mucosal malformations with dilated __________ and inflamed __________
- Common in young people >5 years, also seen in adults – commonly present as rectal polyp with rectal bleeding
o Complications include intestinal obstruction, intussusception, bleeding - Sporadic or can be due to syndromese and Peutz-Jeghers polyp
Peutz-Jeghers polyp – autosomal dominant syndrome
- Cancerous syndrome with mucocutaneous pigmentation and ______ – most common in small bowel
o Unlike other hamartomatous polyps, these are mainly syndromic
- Large pedunculated polyps with a ___________ connective tissue and smooth muscle network on which is normal looking mucosal epithelial tissue
- ___________ is a local complication
- Increased risk of multiple malignancies – 40% lifetime risk, need regular surveillance
o Infancy – testicular sex cord tumours
o Childhood – gastric, small bowel carcinomas
o Adult – colon, pancreas, breast, lung, ovary, uterine carcinomas
mucin filled cysts; lamina propria;
multiple polyps; tree like arborizing; Intussusception
Inflammatory polyps/psuedopolyps – non-neoplastic, made of surviving normal or regenerative colonic mucosa and __________________ surrounded by ulcerations
- Colonic mucosa appears polypoidal relative to the depressed ulceration
o Comprises of reactive epithelium, granulation tissue, fibrosis usually with erosions/ ulcerations
- Commonly on a background of chronic inflammation – IBD (psuedopolyps) particularly ulcerative colitis, diverticulitis
- In rectum – solitary rectal ulcer syndrome (with mucosal prolapse changes)
inflammatory granulomatous tissue;
Adenomas – premalignant neoplastic epithelial lesions
- Defined by presence of dysplastic epithelium – low or high grade
- Sessile or _________ polypoid (mostly) lesions
o Some are flat or depressed with subtle changes in the mucosal texture, colour
- Size – <1cm, but can be larger
o Very small polyps of a few mm can present as a small mucosal bump but can show different patterns when enlarged
- Architecture – ________ (80%), villous with finger like projections, tubulovillous
pedunculated; tubular
Sessile serrated adenoma – premalignant
- Common at the right colon, slightly larger at >5mm
- Sessile soft smooth lesion usually with a blob of mucus – serrations and ____________ of crypts, mild atypia only
- Serrated lesions – lesions with serrated or saw tooth architecture of the epithelial glands
o Hyperplastic polyp
o Sessile serrated adenoma/polyp
o Traditional serrated adenoma – ____________ with dysplasia and serrations
o Surveillance is needed for sessile serrated adenoma/polyp and traditional serrated adenoma as there is a risk for malignancy progression
dilated base;
tubular adenoma
Adenocarcinoma arising in an adenomatous polyp – usually a result of a tubular or tubulovillous adenoma or
adenocarcinoma invading into the submucosa, resulting in malignant polyps
- An invasive carcinoma arising in an adenomatous polyp – samples are obtained from polypectomy and invasive malignancy is usually not suspected
- An increased risk of adverse outcome has been shown to be associated with
o High-grade carcinoma
o Tumour ≥1 mm from the ________________
o Lymphatic or venous vascular invasion
- Malignant polyp of an adenocarcinoma arising in a tubular adenoma (right)
polypectomy resection margin;
Familial adenomatous polyposis – an autosomal dominant (APC gene) (75% inherited), teenagers
- At least 100 polyps by definition – tubular / villous adenomas
- 100% risk of developing colonic adenocarcinoma (by <30yrs) – ___________- can prevent colonic carcinomas but there is still high risk for other GI cancers (stomach, ampulla)
prophylactic colectomy
Colonic carcinoma
- Adenocarcinoma derived from glandular colonic epithelium – most common malignancy of the GI tract
- Accounts for 10% of all cancer related deaths, presents in the 6th to 7th decades unless associated with polyposis syndromes
- Common in western world
- Most common in the _________ area
- Risk factors
o Environmental – ___________ diet, red and processed meats, alcohol, smoking and obesity
o Medical conditions – longstanding and extensive ulcerative colitis, previous ___________
o Genetic – FAP, Lynch syndrome, family history of colonic cancers at young age, multiple sporadic adenomas
rectosigmoid; high fat and low fibre; pelvic radiotherapy
pathogenesis of colorectal carcinomas
1. Adenoma-carcinoma sequence (chronic instability pathway)
- 1st hit of the APC gene in the 2-hit hypothesis is germline or somatic – 2nd hit causes accumulation of β-catenin as APC is now inactivated
o β-catenin translocates to the nucleus and activates Myc and cyclin D1, leading to epithelial cell proliferation
- Further accumulation of mutations include the_________ genes, leading to dysplastic changes
- Mismatch repair pathway (deficiency of mismatch repair genes)
- Unlike the adenoma-carcinoma sequence, there is no gross chromosomal rearrangements or losses
- Accumulation of ____________ in the mismatch repair genes result in MSIH – high microsatellite instability
o Hallmark of Lynch’s syndrome, occurs in 20% of sporadic carcinomas
k-ras and TP53;
missense mutations
Gross appearances of colon carcinomas
1) ______________ lesions
- usually for right colon
- Usually no obstruction as the right colon has a larger diameter
- Slow bleeding may lead to anaemia
2) Circumferential stenosis lesion
- more common at left colon, radiological signs e.g. ______ sign and _______ sign
3) Colonic wall with ulcerative tumour and irregular rugged edges – multiple polyps visible
Polypoidal exophytic;
apple core, napkin ring
Spread of colonic carcinoma
- Through lymph nodes and to several organ via different paths
o Haematogenous spread – to lungs and brain
o Portal vein spread – to liver
- Compared to small vessel infiltration e.g. lymphovascular invasion, invasion of ________ (especially those with smooth muscle or elastic lamina in wall) is a risk factor for liver metastasis, especially if vessels are extramural
- Spread to lung or liver warrants an ____ on TNM staging
larger venous channels; M1
Grading of colorectal carcinomas – by amount of gland formation
Grade Gland formation
1: Well-differentiated (>95% gland formation)
2: Moderately differentiated (50-95% gland formation)
3: Poorly differentiated (<50% gland formation)
4: Undifferentiated (no gland formation or ____; no __________ differentiation)
pT staging of colorectal carcinoma
- A T1 tumour extends into the submucosa, T2 extends to ____________ and T3 shows further extension into _________ or serosa
- A T4a tumour involves the serosa – direct involvement or due to gross perforation of gross bowel through the tumour
- A T4b tumour invades adjacent organs e.g. coccyx and bowel loops
mucin; squamous or neuroendocrine;
muscularis propria; pericolic fat
Circumferential radial margin in colonic carcinoma
- A T4 tumour penetrates through the serosa but some parts of the colon are retroperitoneal and not completely covered by peritoneum
o The circumferential margin must be assessed for any segment either unencased or ___________ by the peritoneum
- Circumferential radial margin – represents the ______________ margin closest to the deepest penetration of tumour and is created surgically by blunt or sharp dissection of the retroperitoneal aspect
o If a tumour has penetrated to the adventitia and reach the point of the circumferential radial margin when it has been surgically excised, there is an increased risk of recurrence by 3.54
o Represents 2x risk of disease in rectocarcinomas
incompletely encased; adventitial soft tissue;
