Pleural Pathology Flashcards
What are the different layers of the pleura?
the visceral pleura lines the lungs
the parietal pleura is the outer layer of pleura
there is a pleural cavity between these 2 layers
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What is the microanatomy of the pleural layers like?
- both layers of pleura (parietal / visceral) consist of connective tissue and mesothelium
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What is the normal mesothelium of the pleura like?
What do they secrete and what is the purpose of this?
a single layer of mesothelial cells lines the pleural cavity
they secrete hyaluronic acid rich pleural fluid
this lubricates the movement of the visceral and parietal pleura against each other during respiration
What are the 3 categories of pleural pathology?
- inflammation - pleurisy or pleuritis
- fibrosis
- neoplasia
What are the causes of pleural inflammation?
primary inflammatory diseases:
- collagen vascular diseases such as SLE & rheumatoid arthritis
infections:
- usually secondary to pneumonia or pulmonary tuberculosis
- viral - primary coxsackie B infection (Bornholm disease)
pulmonary infarction:
- usually secondary to pulmonary arterial thromboembolus
emphysema:
- secondary to ruptured bullae
neoplasms:
- primary or secondary pleural neoplasms
therapeutic:
- pleurodesis usually with talc to treat recurrent pleural effusions or pneumothoraxes
iatrogenic:
- radiotherapy to the thorax
- immune reactions to drugs
If there is no associated pleural effusion, how is pleural inflammation diagnosed?
- pleuritic chest pain - a sharp localised pain exacerbated by breathing
- auscultation of a pleural rub during breathing
What does it usually suggest if there is pleural inflammation and associated pleural effusion?
this describes the presence of excess fluid in the pleural cavity
it usually suggests pleural fibrosis
what are the different types of pleural fibrosis?
- it is usually secondary to pleural inflammation
- unilateral or bilateral
- localised or diffuse
- asbestos associated pleural fibrosis
- parietal pleural fibrous plaques
- diffuse pleural fibrosis
What are the effects of pleural fibrosis?
widespread thick fibrosis can prevent normal lung expansion
compression of the lung during respiration can cause breathlessness
fibrous adhesions can wholly ot partially obliterate the pleural cavity
How can the effects of pleural fibrosis be alleviated?
pleural decortication
this is the removal of fibrous tissue
this improves lung expansion and compression of the lung during respiration
What are parietal pleural fibrous plaques associated with?
What are the symptoms?
associated with low level asbestos dust exposure
they consist of dense poorly cellular collagen and may be visible on chest X-rays
they are asymptomatic
What is diffuse pleural fibrosis associated with?
What is it and what can it cause?
associated with high levels of asbestos dust exposure
it is usually bilateral and consists of dense cellular collagen not extending into interlobal fissures
this prevents normal expansion and compression of the lung during breathing, causing breathlessness
What are the different pathological liquids that may be in the pleural cavities?
- serous fluid - pleural effusion
- pus - empyema or pyothorax
- usually secondary to pneumonia
- blood - haemothorax
- usually traumatic or a ruptured thoracic aortic aneurysm
- bile - chylothorax
- usually traumatic
What is it called if there is air in the pleural cavity?
pneumothorax
What are the 2 different types of pleural effusions?
transudates and exudates
What is the composition of and characteristics of a transudate pleural effusion?
- low capillary oncotic (colloid osmotic) pressure and/or high capillary hydrostatic pressure
- intact capillaries retain semipermeability
- low protein (<2.5 g/dL) & low lactate dehydrogenase
What is the composition of and the characteristics of an exudate pleural effusion?
- normal capillary oncotic pressure and normal vascular hydrostatic pressure
- pathological capillaries lose their semipermeability
- high protein (>2.9 g/dL) and high lactate dehydrogenase
What are the causes of a transudate pleural effusion?
- high vascular hydrostatic pressure
- left ventricular failure
- renal failure
- low capillary oncotic (colloid osmotic) pressure
- hypoalbuminaemia in hepatic cirrhosis, nephrotic syndrome
What are the causes of an exudate pleural effusion?
- inflammation with / without infection
- when does an acute inflammatory effusion become an empyema?
- neoplasms - primary or secondary
What are the symptoms and signs of pleural effusion?
What investigations would support the diagnosis?
symptoms:
- breathlessness - the effusion compresses the lung
- little / no pleuritic pain - the visceral and parietal pleura are not in contact
signs:
- dull to percussion
- reduced breath sounds on auscultation
investigations:
- imaging - ultrasound, CT, chest radiograph
How is breathlessness treated in a pleural effusion?
breathlessness is treated by removing the fluid
- aspiration with a needle and syringe (ultrasound guided)
- reaspirate if the fluid reaccumulates
- for recurrent effusions, consider a temporary or permanent pleural drain
- for recurrent effusions when the lung expands after drainage and the underlying cause remains, consider pleurodesis to obliterate the pleural cavity