Week 6 - RESP Flashcards
Lung Cancers
What is the pathogenesis of lung cancer?
- smoking/carcinogens
- 3p/EGFR mutations
- dysplasia
- more mutations (Kras/C-myc)
- infiltration
- spread
- metastases (p53 mutation)
*normal –> hyperplasia –> metaplasia –> mild dysplasia –>severe dysplasia –> MALIGNANCY
What are the gross and microscopic features of small cell carcinomas?
Gross:
- grey/white, diffuse, infiltrating tumour at hilar region
- spread around bronchi
- infiltrative
- early/rapid spread
Micro:
- irregular, small, dark blue/hyperchromatic cells in sheets
- pleomorphic cells with irregular large nuclei
- scanty cytoplasm
- neuroendocrine cells –> paraneoplastic syndromes
- OAT CELLS
What are the gross and microscopic features of squamous cell carcinomas?
Gross:
- expanding tumour (NOT infiltrating)
- grey/white, nodular, central (hilum)
- spread to LNs/extrapulmonary structures
Micro:
- pleomorphic cells with irregular nuclei forming irregular clusters
- keratin pearl formation/keratinisation of cells
What are the gross and microscopic features of adenocarcinomas?
Gross:
- grey/white, nodular, peripheral tumours
- expanding (NOT infiltrating)
- increase in F/non-smokers
- central scar
- spread to LNs/extrapulmonary structures
Micro:
- pleomorphic cells with irregular dark nuclei forming irregular glands
- areas of necrosis
Which mutations are commonly seen in squamous cell carcinomas vs. adenocarcinomas?
SCC = 3p deletion (increase in males/smokers) Adeno. = EGFR mutation (increase in previous scar pts.)
Compare grade 1 vs. grade 4 cancers?
Grade 1:
- well differentiated
- slow growing
- still gland formation (some cells functioning normally)
Grade 4:
- poorly differentiated (very irregular/pleomorphic)
- fast growing
- NO gland formation
True or False?
3p deletion mutation is seen in normal bronchial epithelium of smokers
True
What are local and systemic clinical features of lung cancer?
Local:
- obstruction (effusions, pneumonias, atelectasis)
- hemoptysis
- bronchiectasis
- SVC obstruction/syndrome
- pancoast tumour
- horner’s syndrome
Systemic:
- cachexia
- paraneoplastic syndromes
- clubbing
- bone pain/epilepsy –> metastases
What is pancoast tumour?
- destructive lesions of thoracic inlet (destruction of ribs 1 + 2)
- involvement of brachial plexus + cervical sympathetic nerves –> severe shoulder pain radiating to axilla/scapulae, atrophy of hand/finger muscles, wrist tenderness, horner’s syndrome, SVC syndrome
What is horner’s syndrome?
- seen in pts. with pancoast tumours
- 3 features:
- Ptosis
- Meiosis
- Anhydrosis
What sign is seen in SVC syndrome? How do you test for it and what indicates a positive sign?
Pemberton’s Sign:
- raise patient’s arms above head for 30s
- a positive test will give rise to flushing/facial swelling, plethora, inspiratory stridor, raised JVP
What is the pathogenesis of hemoptysis in lung cancer?
Cancer proteases break down surrounding tissue and vessels causing haemorrhage
What are Ix. for lung cancer?
Imaging
-CXR, US, MRI, CT, PET scan
Cytology
- sputum
- bronchial lavage
Bronchoscopy/Thoracotomy
Biopsy
-needle/excision
Tumour markers
-epithelial; neuroendocrine
Outline lung cancer cytology for the “big 3”
Adenocarcinoma:
- gland formation
- mucin
Squamous cell carcinoma:
- pink cytoplasm
- keratin pearl formation
Small cell carcinoma:
- little cytoplasm
- nil glands/keratin
- oat cells
True or False?
Carcinoid tumours continuously produce hormones
True
-they have neuroendocrine cells which secrete serotonin and other hormones
What is carcinoid syndrome?
- intermittent diarrhoea
- facial flushing –> dry (no sweating)
- palpitations
- abdominal cramps
- SOB/wheezing
*result of carcinoid tumour
What is a lung hamartoma?
- NOT a true tumour
- it is an embryonic disorganisation
- consists of normal lung tissue BUT in a hapazard arrangement
- round or nodular
- benign behaviour
What are the 2 types of embryonic disorganisation?
- Hamartoma:
- normal tissue in normal place (hapazard arrangement)
- e.g. lung hamartoma - Choristoma:
- normal tissue in abnormal place (ectopic)
- e.g. gastric tissue in appendix
True or False?
There is a latent period of roughly 25-40yrs for mesothelioma to manifest
True
- preceded by fibrous pleural plaques caused by asbestos bodies
- chronic pleural irritation
- encases lung from pleura (literally “squeezes” the lung)
What is broncho-alveolar carcinoma?
- in-situ adenocarcinoma (low grade)
- pneumonic spread –> NO invasion/tissue damage
- tumour cells line alveolar walls
- presents clinically like pneumonia
What is paraneoplastic syndrome?
Clinical symptoms due to “chemical product” released by tumour
*NOT as a result of the tumour itself
What % of lung cancers produce substances which cause paraneoplastic syndromes and which type are they commonest in?
3-10%
-common in small cell lung cancers
What substance can be released by some squamous cell carcinomas?
Parathyroid hormone related peptide (PTH-rp)
-results in paraneoplastic syndrome causing lysis of bone and hypercalcemia!
What paraneoplastic syndromes commonly occur in adenocarcinomas?
Haematologic syndromes
- mucin from tumour causes coagulation of blood
e.g. migratory thrombophlebitis, non-bacterial endocarditis
