Malignant Lung Pathology Flashcards
What is the definition of malignant lung tumours?
tumours within the lung that possess potentially lethal abnormal characteristics that enable them to invade and metastasize / spread to other tissues
What are the 2 different types of malignant lung tumours?
- primary
- secondary
What is the most common type of primary malignant lung tumour?
carcinomas - over 90%
How are lung carcinomas classified?
What are the characteristics of these 2 different types?
they are broadly classified as small cell carcinoma and non-small cell carcinoma
small cell carcinoma:
- less cytoplasm
- nuclear chromatin is fine
- less prominent / no nucleoli
non-small cell carcinoma:
- usually more cytoplasm
- usually clumped / vesicular nuclei
- usually more prominent nucleoli
How are primary lung carcinomas classified based on light microscopy (histology)?
- squamous cell carcinoma (20-30%)
- small cell carcinoma (15-20%)
- adenocarcinoma (30-40%)
- large cell undifferentiated carcinoma (10-15%)
How can each type of primary lung carcinoma be identified from histology?
squamous cell carcinoma:
- cells show keratinisation
adenocarcinoma:
- there is gland formation and/or mucin production
large cell carcinoma:
- non-small cell carcinoma, lacking features of above 2
small cell carcinoma:
- diagnosis made based on nuclear characteristics
What are the other 3 types of primary malignant lung tumours?
carcinoid tumours:
- low grade malignant tumours with better survival
malignant mesenchymal tumours:
- very rare
- most common type of synovial sarcoma
primary lung lymphomas:
- rare
- can be seen in HIV / AIDS patients
How common are secondary lung tumours?
How do they usually present?
they are very common and more common than primary tumours
they usually present as multiple discrete nodules (can also be solitary)
What are the different types of secondary lung tumours?
- sarcomas
- melanomas
- lymphomas
- the most common are carcinomas from various sites (e.g. breast, GI tract, kidney)
What age group and sex tend to be affected by lung cancer?
it is the most common cause of cancer death in the UK and worldwide
M > F but only slightly
it is rare in younger individuals and usually affects 40 - 70 yrs
What is the main risk factor for lung cancer?
What is prognosis and 5-year survival like?
cigarette smoking is a major risk factor
rise in the incidence of lung cancer closely follows an increase in cigarette smoking
overall prognosis is poor with a 5-year survival between 5-10%
What is the aetiology of lung cancer like?
- tobacco smoking
- occupational / industrial hazards
- e.g. asbestos, uranium, arsenic, nickel
- radiation
- e.g. mines in which there is radon
What are other factors involved in the aetiology of lung cancer, not related to lifestyle?
lung fibrosis:
- increased risk of lung cancer in patients with pulmonary fibrosis
genetic mutations:
- EGFR, KRAS, ALK
- usually seen in lung cancers in patients who have nerve smoked
What is the pathogenesis of lung cancer?
pathogenesis is not very well understood
involves mutations in key genes regulating cell proliferation, DNA repair and apoptosis
How does cigarette smoking influence squamous carcinoma?
cigarette smoking is an irritant in squamous carcinoma
- squamous metaplasia
- dysplasia
- carcinoma in-situ
- frank squamous carcinoma
what is the relationship between quantity of cigarettes smoked and risk of lung cancer?
tobacco smoke is a carcinogen
there is almost a linear dose relationship between the number of cigarettes smoked daily and the risk of developing lung cancer
passive smoking also increases risk
What is 1 pack year?
1 pack year is equivalent to 20 cigarettes per day for 1 year
(or 40 cigarettes per day for 6 months)
What types of respiratory illness is asbestos associated with?
it is associated with lung cancer, as well as:
- lung fibrosis
- mesothelioma (malignant tumour of the pleura)
What is the risk of lung cancer with asbestos in combination with cigarette smoking?
What is the latent period?
in combination with cigarette smoking the risk is increased (20 - 100 fold)
the latent period is about 20 years between exposure to asbestos and development of carcinoma
What are the clinical features of lung carcinoma due to?
- local effects of the tumour
- distant metastases
- non-specific features
- asymptomatic and discovered incidentally
Where does lung cancer tend to spread to?
What are some of the symptoms related to metastasis?
- lymph nodes
- cerebral metastases
- epilepsy
- bone metastases
- hypercalcaemia
- pain and fracture
What are some of the symptoms of lung cancer?
- haemoptysis and malignant cells in sputum
- finger clubbing
- weight loss / cachexia
endocrine effects:
- increased ACTH
- increased ADH
- increased PTH
What are the main local effects of lung cancer?
haemoptysis:
- central tumours arising in proximal airways can ulcerate and bleed
breathlessness / features of pneumonia:
- tumour obstructing the airways with distal collapse or consolidation
What local effects of lung cancer may be caused by a tumour infiltrating into adjacent structures?
- pleura - pleural effusion presenting as breathlessness
- chest wall / ribs - pain
- recurrent laryngeal nerve - hoarseness
- sympathetic chain - Horner’s syndrome
- oesophagus - dysphagia
what are the common sites of distant metastases of lung cancer?
How do they tend to present?
- lymph nodes
- pleura
- liver
- bone
- adrenal glands
- brain
- can present with disseminated disease
- depending on the site, can present with pathological fractures, seizures, lumps in the neck, etc.
What are the non-specific features of lung cancer?
- usually metabolic effects
- weight loss & lethargy
- electrolytic disturbances
- hyponatraemia, hypokalaemia & hypercalcaemia in small cell carcinoma
- finger clubbing
What is meant by lymphangitis carcinomatosa?
lymphatics within the lung are diffusely involved by tumour
this is inflammation of the lymph vessels caused by malignancy
What is the treatment for early stage lung cancer and advanced disease?
early stage:
- small % of patients are diagnosed when the disease is limited to the lung or extension into local nodes
- surgery or radical radiotherapy
advanced disease:
- chemotherapy
- palliative radiotherapy
What are the new treatments for lung cancer with advanced disease?
- targeted therapy
- treatment based on tumour genomics (e.g. EGFR mutations)
- immune checkpoint inhibitors
