Respiratory Pathology Flashcards
What proportion of children are diagnosed with asthma?
1 in 10 UK children
What percentage of the UK population have COPD?
5%
What type of epithelium lines the conducting airways?
Pseudostratified cilliated columnar mucus secreting epithelium
How do you define respiratory failure?
PaO2
What is type I respiratory failure?
(paCO2
What is type II respiratory failure?
(paCO2>6.3kPa)
Hypercapnic respiratory drive
What is a cough?
Reflex response to irritation
What causes stridor?
Proximal airway obstruction
What causes wheeze?
Distal airway obstruction
What causes pleuritic pain?
Pleural irritation
What causes cyanosis?
Decreased oxygenation of haemoglobin
What can we find out using percussion?
Dull – Lung consolidation or pleural effusion
Hyperesonant – Pneumothorax or emphysema
On auscultation, what do crackles mean?
Resisted opening of small airways
On auscultation, what does wheeze mean?
narrowed small airways
On auscultation, what does bronchial breathing mean?
Sound conduction through solid lung
On auscultation, what does pleural rub mean?
Relative movement of inflamed visceral & parietal pleura
Which vascular diseases are associated with the lungs?
pulmonary embolism,
pulmonary hypertension
What is a benign lung tumour called?
adenochondroma
rare
What type of tumour makes up 90% of lung tumours?
carcinoma
What percentage of lung cancer is due to smoking?
80%
What are the risk factors for lung cancer?
cigarettes (80%)
secondary cigarette smoke - 10-30% increase
asbestos, high level exposure, with or without asbestosis
In UK about 2000 cases per year, 10% of male lung carcinomas
lung fibrosis – including asbestosis and silicosis
radon Schneeberg mines (in 1879 the first description of occupational lung cancer) , igneous rocks - Aberdeen
chromates, nickel, tar, hematite, arsenic, mustard gas
What is asbestos?
Fibrous metal silicates, 5-100μm x φ 0.25−0.5μm
Amphiboles - blue asbestos (crocidolite) – the most dangerous
brown asbestos (amosite)
Serpentines - white asbestos (chrysotile)- the least dangerous
High level exposure produces pulmonary interstitial fibrosis
asbestosis
Asbestos bodies seen by light microscopy
Fibres coated with mucopolysacharide & ferric iron salts
What are the two types of carcinoma?
non-small cell carcinoma (85%) squamous carcinoma 52% adenocarcinoma 13% large cell neuroendocrine carcinoma undifferentiated large cell carcinoma
small cell carcinoma (15%)
all are neuroendocrine
Multiple differentiation is common
What are carcinoid tumours?
Low grade neuroendocine epithelial tumours
How is it determined if a lung tumour is primary or secondary?
History Morphology some adenocarcinomas, but not squamous Antigen expression Immunocytochemistry is useful but not 100% reliable
Where are most lung carcinomas?
Most central, main or upper lobe bronchus (bronchogenic)
Adenocarcinoma more peripheral
scar cancers or cancer with a fibrous (desmoplastic) reaction?
Key points on Squamous carcinoma
desmosomes link cells like epidermis (‘epidermoid’)
+/- keratinization
~90% in smokers
central > peripheral
hypercalcaemia due to parathyroid hormone related peptide
What type of epithelium are the bronchi lined by?
The normal bronchus is lined by pseudostratified columnar epithelium with ciliated and mucus-secreting cells
What is Squamous metaplasia?
Irritants such as smoke cause the epithelium to undergo a reversible metaplastic change from pseudostratified columnar to stratified squamous type which may keratinize (like skin)
What is dysplasia?
One metaplastic cell undergoes irreversible genetic changes (a series of sequential somatic mutations of oncogenes & anti-oncogenes) producing the first neoplastic cell
How does dysplasia develop?
The neoplastic cell proliferates more sucessfully than the metaplastic cells
The neoplastic clone relaces the metaplastic cells producing dysplasia (intraepithelial neoplasia or carcinoma-in-situ)
What are the paraneoplastic effects of lung carcinomas?
Cachexia
Skin - acanthosis nigricans, tylosis
Hypertrophic pulmonary osteoarthropathy (clubbing)
Coagulopathies - thrombophebitis migrans
Encephalomyelitis, neuropathies & myopathies
- Lambert Eaton myasthenic syndrome due to anti-neuromuscular junction autoantibodies in small cell carcinoma
Endocrine effects
- Parathyroid hormone-related peptide from squamous cell carcinoma causing hypercalcaemia
- ACTH and antidiuretic hormone from small cell carcinoma
- 5-hydroxytryptamine - carcinoid (uncommon)
What is classed as T1 stage lung malignancy?
T1a=
What is classed as T2 stage lung malignancy?
T2a=3-5cm
T2b=5-7cm
> 2cm to carina
lobar atelectasis or obstructive pneumonia to hilus
What is classed as T3 stage lung malignancy?
> 7cm
What is classed as T4 stage lung malignancy?
tumour in carina
invasion - heart, great vessels, trachea, oesophagus, spine
nodules - in other ipsilateral lobes
What are “epidermal growth factor receptor tyrosine kinase inhibitors”?
Gefitinib (Iressa) and erlotinib (Tarceva) are ATP analogues that inhibit EGFR-TK if activating mutations are present
Oral medication, less toxic than standard cytotoxic chemotherapy
Inhibition of EGFR TK mediated protein phosphorylation and activation of the mitotic cycle
Sensitising mutations present in 10% of non-small cell lung cancers and are commoner in adenocarcinomas in non-smoking Asian women
Not curative but stabilises progression until resistance mutations develop
What is crizotinib?
ATP analog inhibits ALK, ROS1, c-Met (Hepatocyte Growth Factor receptor /HGFR) tyrosine kinases.
Temporary control – no progress or regress
Effective in about 90% of tumours with ALK-EML fusion gene FDA approval Aug 2011 for late stage (local advanced or metastatic) NSCLC
>$100,000 per patient per year
UK approval expected
What are the different types of pleural cavity problems called?
Pneumothorax = air tension pneumothorax Pleural effusion (hydrothorax) - transudate or exudate Haemothorax = blood Chylothorax = lymph Empyema (prothorax) = pus
What are the main causes of pleural effusion?
Inflammatory:
- Serous/fibrinous –exudate
- Due to inflammation/infection in adjacent lung
Non inflammatory:
- Congestive Cardiac Failure – transudate
LDH, pH, Glucose of fluid can be measured to suggest a diagnosis
Cytology used to assess the presence of malignant or inflammatory cells