Common GI malignancies and imaging of the GI tract Flashcards
Where in the oesophagus can you get adenocarcinomas?
Lower third
What is adenocarcinoma?
A malignant tumour formed from glandular structures in epithelial tissue
What is the cause of adenocarcinomas in the lower oesophagus?
Metaplasia over time of normal squamous epithelium to columnar epithelium (containing goblet cells) caused by the chronic reflux of acid into the oesophagus (Barrett’s oesophagus)
Where in the colon would cancer most likely result in a patient presenting with bowel obstruction?
Sigmoid colon
What do right-sided colon tumours tend to be like?
Fungating, exophytic (grow outwards from bowel wall) and prone to bleeding but do not normally cause bowel obstruction. Also the content of the bowel is less solid at this stage - contains more water, therefore is less likely to get blocked.
What do left-sided colon tumours tend to be like?
To grow circumferentially around the lumen of the bowel and cause stenosis and therefore more likely to be blocked. In addition the colons contents are more solid at this stage as more water has been reabsorbed.
What is a commonly used staging system for many cancers?
TNM staging system
In the TNM staging system, what does T stand for?
T describes the primary tumour and the extent of growth
In the TNM staging system, what does N stand for?
N describes the regional lymph node involvement
In the TNM staging system, what does M stand for?
M describes the presence (or not) of distant metastasis
A signet ring cell is a type of cell found on histological images of gastric adenocarinoma. In which histological classification of gastric cancer is it found?
Diffuse type carcinoma
What creates the distinctive appearance of a signet ring cell in certain forms of diffuse gastric cancer?
These cells have had their nucleus pushed to the periphery due to accumulation of intracellular mucin
Describe what happens in diffuse carcinomas
They are usually composed of chains of single cells which invade the wall of the gut without a sharply defined invasive margin
How do intestinal type carcinomas differ from diffuse type carinomas?
Intestinal type carcinomas develop a more glandular structure lined by mucus secreting cells. They tend to have a better define margin than diffuse type carcinomas
What is the most common location for a lymphoma to develop within the GI tract?
Stomach (whilst still fairly rare). They seem to have strong links with H-pylori and in a few cases can be shrunk by eradication the bacteria
What is a lymphoma?
any of a group of blood cell tumors that develop from lymphatic cells
What type of rare pancreatic cancer would cause the patient to have a low blood sugar?
Insulinoma
What is the name of the tumour that causes Zollinger-Ellinson syndrome?
Gastrinoma which produces gastrin. Increased gastrin stimulates an increase in HCl production by the parietal cells and causes severe ulceration of the stomach and small intestine
What is another type of rare pancreatic islet cell cancer, other than insulinoma?
Glucagonoma - secretes excess glucagon
Although largely replaced by TMN staging criteria, Dukes staging (A-D) is still a useful way of thinking about colorectal cancer. What Dukes staging describes a tumour that has penetrated through the muscle layer in the bowel wall?
B - The tumour has gone through the bowel wall but there are no lymph nodes involved
What is the C stage of Dukes staging?
C - Lymph nodes are involved
What is the D stage of Duke’s staging?
D - widespread metastasis
What happens to the 5 year survival rate from cancer as Dukes staging goes from A-D?
It decreases
Where in the oesophagus can you get a adenocarcinoma?
Lower third - if metaplasia from squamous epithelia to columnar epithelia has happened over time (Barrett’s oesophagus) due to chronic reflux, adenocarcinomas (cancer in glandular epithelia) can occur.