Pathology of the respiratory system Flashcards
What kind of epithelium do conducting airways have?
Pseudostratified columnar
What epithilium would you find in alveoli?
Mostly flat Type I pneumocytes (gas exchange) & some rounded Type II pneumocytes (surfactant production)
What is respiratory failure?
Having a PaO2 of less than 8.0kPa
What is type I respiratory failure?
- (paCO2<6.3kPa)
- Hypoxic respiratory drive
What is type II respiratory failure?
- (paCO2>6.3kPa)
- Hypercapnic respiratory drive
What is the cause of cough?
Reflex response to irritation
What is the cause of stridor?
Proximal airway obstruction
What is the cause of wheeze?
Distal airway obstruction
What is the cause of pleuritic pain?
Pleural irritation
What is the cause of dyspnoea?
Impaired alveolar gas exchange?
What is the cause of cyanosis?
Decreased oxygenation of haemoglobin.
What is the cause of weight loss in respiratory illness?
Catabolic state with chronic inflammation or tumours.
What is the cause of crackles on ascultation?
Resisted opening of small airways.
What is the cause if brochial breathing on auscultation?
Sound conduction through solid lung.
What is the cause if pleural rub on auscultation?
Relative movement of inflamed visceral & parietal pleura.
What is the cause of dull percussion?
Lung consolidation or pleural effusion.
What is the cause of hyperesonant percussion?
Pneumothorax or emphysema.
Give an example of a primary benign lung tumour.
Adenochondroma - rare.
What percentage of lung cancer deaths in the UK are due to smoking?
80%
What are the 2 and 5 year survival rates for lung cancer in Yorkshire?
10% and 6%
What are the risk factors for lung cancinoma?
Tobacco 80%
Secondary smoke 10% - 30%
Asbestos 10% (usually male)
Lung fibrosis - including asbestosis and silicosis
Radon (Miners, igneous rocks, gas from ground accumulates in homes)
Cromates, nickle, tar, haematite, arsenic, mustart gas
What is the body’s initial response to high levels of asbestos?
Pulmobary interstitial fibrosis - asbestosis.
What is the main association between asbestos and lung carcinomas?
Higher incidence of all types of lung carcinoma associated with high level exposure to asbestos
What are the hypotheses regarding asbestos and lung carcinoma?
– Fibrosis – no increased risk without asbestosis
– Fibre burden - dose related, some risk at all exposure level
What is the epidemiological evidence for the link between asbestos and lung carcinoma?
•For
–Increased risk in workers exposed to asbestos
–Increased risk in the absence of “small opacities” on CXR in asbestos exposed workers
•Against
–No increased risk in low level exposed workers or Canadian asbestos mining towns inhabitants with no occupational exposure
What are the various types of non-small cell carcinoma (85% of primaries)?
squamous carcinoma 52%
adenocarcinoma 13%
large cell neuroendocrine carcinoma
undifferentiated large cell carcinoma
What type of tumours are small cell carcinomas?
Neuroendocrine
What kind of tumours are carcinoid?
Low grade neuroendocine epithelial tumours
What other primary malignant tumours are possible?
Lymphomas, sarcomas, carcinosarcomas.
What are the commonest tumours of the lung?
Metastases
What are the gross features of lung metastases?
Typically multiple bilateral nodules but can be solitary
How can you tell the difference between a primary and a secondary tumour of the lung?
- History
- Morphology
– some adenocarcinomas, but not squamous
•Antigen expression
–Immunocytochemistry is useful but not 100% reliable
What are the features of squamous cell carcinoma?
- desmosomes link cells like epidermis (‘epidermoid’)
- +/- keratinization
- ~90% in smokers
- central > peripheral
- hypercalcaemia due to parathyroid hormone related peptide
What kind of epithelium is bronchial epithelium?
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.
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 features of adenocarcinoma?
- glandular cells, serous or +/- mucus vacuoles, in acinar, tubular, solid or papillary structures
- central = peripheral
- ~80% in smokers
- Thyroid transcription factor (TTF) is expressed in many non-mucinous lung adenocarcinomas
What is brochioalveolar carcinoma?
- Spread of well differentiated mucinous or non-mucinous neoplastic cells on alveolar walls
- Not invasive - “adenocarcinoma in situ”
- Mimics pneumonia
- Uncommon nodal & distant metastases
What is the name of the neuroendocrine cells normally found in normal lung mucosa?
Kulchitsky cells
What is the first stage in the development of neuroendocrine tumours of the lungs?
Intraepithelial neuroendocrine cell hyperplasia & carcinoid tumourlets (
What type of neuroendocrine tumours are known?
Carcinoid, atypical carcinoid, large cell neuroendocrine carcinoma and small cell carcinoma
What are the features of typical carcinoid tumours?
- Often grow into and occlude a bronchus
- Organoid, bland cells, no necrosis,
- Associated with multiple endocrine neoplasia syndrome type 1
- Not associated with smoking
- Not “benign” may invade lymphatic vessels and nodes but rare distant metastases 6-9% to hilar nodes, less to distant sites, 95% 5yr survival
What are the features of atypical carcinoid tumours?
- 11% of lung carcinoids
- Less organoid, more atypia, nucleoli - may be focal atypia in an otherwise typical carcinoid
- Necrosis, 2-10 mitotic figure per 2sqmm
- More aggressive than typical carcinoids
– 70% metastasise
– 60% 5yr survival
What are the features of large cell neuroendocrine tumours?
•Neuroendocrine morphology
– organoid architecture, eosinophilic granular cytoplasm
– antigen expression
- Severe atypia, nucleoli, necrosis, >11 mitotic figures per 2sqmm
- Prognosis similar to or worse than other non-small cell lung carcinomas
- Associated with smoking
What are the features of small cell carcinomas?
- Rapidly progressive malignant tumours
- Neurosecretory granules with peptide hormones such as ACTH
- May have small primary with metastases before presentation
- ~99% in smokers
- No “small cell carcinoma in situ” identified