7 - Respiratory Pathology Flashcards
What is the most common cause of lung cancer?
smoking (contains carcinogens)
what is the first diagnostic test used for lung cancer?
chest x-ray or CT scan
subtle symptoms—–> chest x-ray
major symptoms/over the age of 50—–> CT scan
What are the clinical features of lung cancer?
haemoptysis finger clubbing cough shoulder/chest pain dyspnoea hoarseness
What test is done to get a sample of the tumour?
bronchoscopy
NOTE: sample the tumour with the highest staging
What is the first thing to look at when you have a sample of a tumour?
is it small cell or non-small cell cancer?
What classification is used to stage tumours? What does this represent?
TNM classsification TUMOUR -size of the tumour -where it is located - adjacent structures NODE - if tumour has spread to lymph nodes METASTASES - if the tumour has spread to other organs
Why would a PET scan be used?
shows activity
allows us to see the spread of suspected tumour to other organs
what is a trans-thoracic CT biopsy?
give some advantages and disadvantages
a needle is inserted into the chest guided by a CT scan
/ real time / sensitivity 70-100% x risk of pneumothorax x small sample area x in case of bleeding, there is no immediate intrabrochial treatment possible
If the tumour is local, what is the best treatment?
Surgery
If there is advanced disease with lymph node involvement, what is the best treatment?
Start with chemotherapy to try and reduce the extent of spread
What is minimum length of a tumour at which it can be detected?
10 mm
Why is lung cancer hard to detect?
Most patients are asymptomatic
what are histology and cytology?
histology - looking at tissues
cytology - looking at individual cells
what is the most common type of malignant lung tumour?
epithelial tumours
other than smoking, what other risk factors are there for lung cancer?
- asbestos exposure
- radiation
- genetic predisposition
- other e.g. occupation (heavy metal)
what are the two groups that common malignant epithelial tumours of the lung split up into?
which is the worse type?
small cell and non small cell carcinoma
small cell carcinoma has a much worse prognosis than non-small cell carcinoma
What is the most common form of lung cancer in non-smokers?
adenocarcinomas
what are the most common types of malignant lung cancers in the mediastinum and the peripheral airways?
mediastinum/large airways - small cell carcinoma
peripheral arteries - adenocarcinoma
Up to what stage are carcinomas reversible?
(low grade) dysplasia
how does smoking contribute to the development of squamous cell carcinomas?
- the airway epithelium reacts to chronic irritation of cigarette smoke - it becomes tougher
- ciliated epithelium is delicate—–> when it is repeatedly exposed to smoke it will change into squamous epithelium
- lack of cilia = mucus is not removed from the lungs (smokers cough) and carcinogens accumulate
- the squamous cells acquire mutations so the normal pattern of growth is disrupted
- the dysplasia becomes more disrupted until it becomes a carcinoma in situ
- a further mutations will make it invasive
What are adenocarcinomas formed from?
glandular epithelium
What is an atypical adenomatous hyperplasia?
precursor lesion of an adenocarcinoma
proliferation of atypical cells lining the alveolar walls. Increases in size and can eventually become invasive.
Why is the incidence of adenocarcinomas increasing?
they develop in the periphery-
increasing in incidence because there is deeper inhalation of cigarette smoke and because it is more common in non-smokers
what happens during an adenocarcinoma?
- alveolar walls thicken and they are lined by atypical cells
- over time, some of the cells will grow large
- at some point, the cells will mutate and form enzymes that will break down the stroma
- (formation of fibrous scars) is accompanied by inflammation
NOTE: invasive tumours can metastasise and break down elastin in the BM to form fibrous stroma
Do adenocarcinomas metastasise early or late?
early
What is the worst form of lung cancer?
small cell carcinomas
NOTE: very rare in non-smokers
What percentage of all lung cancers are small cell?
20-25%
Why do small cell carcinomas often become necrotic?
they divide so fast that they often outgrow the blood supply
Why is chemotherapy used often to target small cell carcinomas?
- very chemosensitive
- it has usually spread by the time it has been identified
What is a proximal tumour most likely to be?
What physical effects can this have?
squamous cell carcinoma or small cell carcinoma
causes bronchial obstruction, which can lead to collapse of the distal lung and impaired drainage of the bronchus
What is a paraneoplastic syndrome?
systemic effect of a tumour due to abnormal expression by tumour cells of factors (e.g. hormones) NOT normally expressed by the tissue from which the tumour arose
(i.e. a tumour expresses proteins that it would not normally express)
What is a mesothelioma?
a type of cancer that develops from the thin layer of tissue that covers many of the internal organs (known as the mesothelium). The most common area affected is the lining of the lungs and chest wall.
What is a carcinoma?
a cancer of the epithelial tissue