Pathology- Colorectal Carcinoma Flashcards
what is between the epithelium and crypts (mucosa) and the muscularis mucosae in the large bowl
stem cells
what is a polyp
a protrusion of growth above the epithelial surface- a growth nodule
is a polyp benign or malignant
can be either- most are benign
give examples of benign epithelial polyps
neoplastic- adenocarcinoma (most important)
inflammatory (IBD)
metaplastic/hyperplastic
give examples of malignant epithelial polyps
polypoid- adenocarcinomas
carcinoid polyps
give examples of benign mesenchymal polyps
lipoma
give examples of malignant mesenchymal polyps
sarcomas
what are the differential diagnosis of a colonic polyp
- adenoma
- serrated polyp
- polypoid carcinoma
- other
(need histology to tell them apart)
what are the types of polyp
pedunculated (hangs on a stalk- easiest to remove and treat if cancerous)
sessile (slightly raised)
flat
what are the features of a polyp
irregular surface, long stalk, have normal submucosa that has been heaped into a growth
what is a dysplatic epithelial lining
disorganised growth, uncontrolled epithelial proliferation- mostly columnar, don’t really product crypts
describe an adenoma of the colon
benign tumours, not invasive- do not metastasise, but are precursors for adenocarcinomas if left unchecked
are all adenomas dysplastic
yes- appear darker in microscopy due to increased DNA
what are the precursors for colorectal carcinomas
adenomas
give an example of a mutation that causes an adenoma to become an invasive adenocarcinoma
p53 mutation
what is p53
tumour suppressor- cellular tumour antigen
why must all adenomas be removed and how
as they are all premalignant- endoscopically or surgically (if patient fit enough)
what are the different microscopic structures of adenoma polyps
tubullovillous, villous, tubular
describe the action of malignant cells in a adenocarcinoma
grow and produce gland (circular collects) and destroy the healthy tissue in their path
what is the necrosis pattern in a tumour of the large bowl described as
dirty
what does dukes staging predict
prognosis
what is dukes staging
Dukes A: Confined by muscularis propria
Dukes B: Through muscularis propria to
reach mesenteric adipose tissue
Dukes C: Metastatic to lymph nodes
where are the majority of colorectal carcinomas
left side (rectum, sigmoid, descending)- 75%
right side (caecum, ascending)- 25%
what can the presenting complaints of a left sided colorectal carcinoma be
blood pressure, altered bowl habits, obstruction
what can the presenting complaints of a right sided colorectal carcinoma be
anaemia, weight loss- not obstruction as in caecum tumour has large area to grow
describe the gross appearance of a colorectal carcinoma
varied- polypoid, stricturing, ulcerating
raised rolled edges
what happens when a tumour occludes the bowl
constipation and diarrhoea and bowl pushes through liquid material only
what can a caecal mass breach
mesenteric fat
describe the pattern of spread of a colorectal carcinoma; local invasion
mesorectum, oeritoneum, other organs
describe the pattern of spread of a colorectal carcinoma; lymphatic spread
mesenteric nodes lymph nodes of mesorectum)
describe the pattern of spread of a colorectal carcinoma; haematogenous
liver (via portal system), distant sites
what are the two types of inherited colorectal cancer syndromes
heriditary- non polyposis coli (<100 polyps) HNPCC
familial- adenomatous polyposis (>100 polyps) FAP
describe HNPCC
late onset, autosomal dominant, defect in dna repair, right sided tumours, crohns like inflammatory response
descibe FAP
early onset, autosomal dominant, defect in tumour supressor, throughout colon, no specific inflammatory response
how long does it take polys to turn into cancer
3-5 years
what is the aeitology of colorectal cancer
mutation in APC gene, mutation of p58 gene, autosomal dominant inheritance
predisposing conditions (long standing IBD, adenomatous polyps)
lifestyle factors (red/processed meat, smoking, alcohol, obesity)
what are the chronic symptoms pf colorectal cancer
change in bowel habit, colicky abdo pain, iron deficiency anaemia, rectal bleeding, weight loss, abdo mass, bowel
emergency symptoms: obstruction/bleeding
name a benign colorectal neoplasia
adenoma
name a malignant colorectal neoplasia
adenocarcinoma
where is the most common places for a colorectal neoplasia
rectum then sigmoid, colon, caecum
what are the different types of colorectal polyp
inflammatory, hamartomatous (local malformation), metaplastic, neoplastic (adenoma)
what genes are assocaited with cancer
oncogenes (mutation causes excess growth and division- gain of function)
tumour suppressor genes (mutation allows excess growth and division-loss of function)
HNPCC
what is APC
a tumour suppressor gene
what is kras
a mutated gene found in 30-50% of all colorectal cancers
what are the macroscopic appearances of colorectal cancer pathology
polypoidal, ulcerative, annular
describe the histology of adenomas
tubular, villous
describe the histology of adenocarcinomas
have different degrees of differentiation
how are cancers pathologically staged
dukes (A,B,C,D), TNK
what does a stage III cancer mean
it has invaded through the muscularis
what does the T1,2,3,4 stages mean in TNM colorectal staging mean
T1 - submucosa only
T2 - into muscle
T3 - through muscle
T4 - adjacent structures (including peritoneum)
what does N means in TNM staging
N0- no lymph node involvement
N1 - < 3 nodes involved
N2 - > 3 nodes involved
what does M means in TNM staging
presence or not of distant metastases
how does colorectal cancer spread
local, lymphatic, blood, transcoelomic (peritoneal cavity)
what lifestyle factors protect you from colorectal cancers
vegetables, fibre, exercise
what symptoms are likely to arise from cancer in the caecum
anaemia
what symptoms are likely to arise from cancer in the descending colon
pain, change in bowel habit, rectal bleeding
what symptoms are likely to arise fro cancer in the rectum
rectal bleeding tenesmus
what are the general clinical findings of colorectal cancer
anaemia, cachexia, lymphadenopathy
what clinical signs are found in the abdomen in colorectal cancer
mass, hepatomegaly, distension
what clinical signs are found in the rectum in colorectal cancer
mass, blood
what investigations are used to diagnose colorectal cancer
barium enema, CT colonography, sigmoidoscopy, colonoscopy
what is the benefit of a colonoscopy
can do diagnosis and treatment at same time
how far do the sigmoidoscopy and colonoscopy reach
sigmoidoscopy reaches to splenic flexure
colonoscopy reaches to the caecum
what is faecal occult blood testing (FOBT) used for
used to detect colon cancer and other disease
what are the staging investigations for lung and liver cancer
CT scan
what is the staging investigation for primary rectal cancer
MRI
what is the prep for a CT colonscopy
bowel prep and faecal tagging (ingestion of a contrast)
what is the e,ergency presentation of colorectal cancer
obstruction (distention, absolute constipation, pain, vomiting), bleeding, perforation
how are obstructions treated
colostomy alone, resection + colostomy, resection + anastomoses, stenting
what is the treatment for colorectal cancer
surgery , radiotherapy, chemotherapy
can surgery be done on rectal cancer
yes- anterior resection or abdomino-perineal excision
when is radiotherapy used in rectal cancer
as an adjuvant pre or post op or as a palliative measure
when is chemotherapy used in colorectal cancer
adjuvamt for stage c
for advance disease
what are the new agents for advanced colorectal disease
oxaliplatin, irinotecan and biological agents
