Malignant Lung Pathology

Question 1

What is the definition of malignant lung tumours?

Answer 1

tumours within the lung that possess potentially lethal abnormal characteristics that enable them to invade and metastasize / spread to other tissues

Question 2

What are the 2 different types of malignant lung tumours?

Answer 2

1. primary
2. secondary

Question 3

What is the most common type of primary malignant lung tumour?

Answer 3

carcinomas - over 90%

Question 4

How are lung carcinomas classified?

What are the characteristics of these 2 different types?

Answer 4

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

Question 6

How are primary lung carcinomas classified based on light microscopy (histology)?

Answer 6

• squamous cell carcinoma (20-30%)
• small cell carcinoma (15-20%)
• adenocarcinoma (30-40%)
• large cell undifferentiated carcinoma (10-15%)

Question 7

How can each type of primary lung carcinoma be identified from histology?

Answer 7

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

Question 9

What are the other 3 types of primary malignant lung tumours?

Answer 9

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

Question 10

How common are secondary lung tumours?

How do they usually present?

Answer 10

they are very common and more common than primary tumours

they usually present as multiple discrete nodules (can also be solitary)

Question 11

What are the different types of secondary lung tumours?

Answer 11

• sarcomas
• melanomas
• lymphomas
• the most common are carcinomas from various sites (e.g. breast, GI tract, kidney)

Question 12

What age group and sex tend to be affected by lung cancer?

Answer 12

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

Question 13

What is the main risk factor for lung cancer?

What is prognosis and 5-year survival like?

Answer 13

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%

Question 14

What is the aetiology of lung cancer like?

Answer 14

• tobacco smoking
• occupational / industrial hazards
  
  • e.g. asbestos, uranium, arsenic, nickel
• radiation
  
  • ​e.g. mines in which there is radon

Question 15

What are other factors involved in the aetiology of lung cancer, not related to lifestyle?

Answer 15

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

Question 16

What is the pathogenesis of lung cancer?

Answer 16

pathogenesis is not very well understood

involves mutations in key genes regulating cell proliferation, DNA repair and apoptosis

Question 17

How does cigarette smoking influence squamous carcinoma?

Answer 17

cigarette smoking is an irritant in squamous carcinoma

1. squamous metaplasia
2. dysplasia
3. carcinoma in-situ
4. frank squamous carcinoma

Question 18

what is the relationship between quantity of cigarettes smoked and risk of lung cancer?

Answer 18

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

Question 19

What is 1 pack year?

Answer 19

1 pack year is equivalent to 20 cigarettes per day for 1 year

(or 40 cigarettes per day for 6 months)

Question 20

What types of respiratory illness is asbestos associated with?

Answer 20

it is associated with lung cancer, as well as:

• lung fibrosis
• mesothelioma (malignant tumour of the pleura)

Question 21

What is the risk of lung cancer with asbestos in combination with cigarette smoking?

What is the latent period?

Answer 21

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

Question 22

What are the clinical features of lung carcinoma due to?

Answer 22

• local effects of the tumour
• distant metastases
• non-specific features
• asymptomatic and discovered incidentally

Question 23

Where does lung cancer tend to spread to?

What are some of the symptoms related to metastasis?

Answer 23

• lymph nodes
• cerebral metastases
  
  • epilepsy
• bone metastases
  
  • ​hypercalcaemia
  • pain and fracture

Question 24

What are some of the symptoms of lung cancer?

Answer 24

• haemoptysis and malignant cells in sputum
• finger clubbing
• weight loss / cachexia

endocrine effects:

• increased ACTH
• increased ADH
• increased PTH

Question 25

What are the main local effects of lung cancer?

Answer 25

haemoptysis:

• central tumours arising in proximal airways can ulcerate and bleed

breathlessness / features of pneumonia:

• tumour obstructing the airways with distal collapse or consolidation

Question 26

What local effects of lung cancer may be caused by a tumour infiltrating into adjacent structures?

Answer 26

• pleura - pleural effusion presenting as breathlessness
• chest wall / ribs - pain
• recurrent laryngeal nerve - hoarseness
• sympathetic chain - Horner’s syndrome
• oesophagus - dysphagia

Question 27

what are the common sites of distant metastases of lung cancer?

How do they tend to present?

Answer 27

• 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.

Question 29

What are the non-specific features of lung cancer?

Answer 29

• usually metabolic effects
• weight loss & lethargy
• electrolytic disturbances
  
  • hyponatraemia, hypokalaemia & hypercalcaemia in small cell carcinoma
• finger clubbing

Question 30

What is meant by lymphangitis carcinomatosa?

Answer 30

lymphatics within the lung are diffusely involved by tumour

this is inflammation of the lymph vessels caused by malignancy

Question 31

What is the treatment for early stage lung cancer and advanced disease?

Answer 31

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

Question 32

What are the new treatments for lung cancer with advanced disease?

Answer 32

• targeted therapy
• treatment based on tumour genomics (e.g. EGFR mutations)
• immune checkpoint inhibitors