Pleural Pathology Flashcards
Describe the layers of the pleura from the lung to the intercostal muscles
- Lung
- Connective tissue
- Mesothelium
- Pleural cavity
- Mesothelium
- Connective tissue
- Intercostal muscles
What cells line the pleural cavity?
A single layer of mesothelial cells (either side)
What do the mesothelial cells of the pleura secrete?
Pleural fluid
What does pleural fluid consist of?
hyaluronic acid-rich mucinous pleural fluid
Function of pleural fluid?
lubricates the movement of the visceral and parietal pleura against each other during respiration
What are the 2 names for the inflammation of the pleura?
Pleurisy or pleuritis
Which type of 1ary inflammatory diseases can cause pleurisy?
Collagen vascular diseases:
- systemic lupus erythematosus (SLE)
- rheumatoid arthritis
Pleurisy can also occur 2ary to infections. Which 3 infections predispose to pleurisy?
- Pneumonias
- Pulmonary TB
- Viral: primary Coxsackie B infection (Bornholm disease)
Pulmonary infarction can give rise to pleurisy. What is this usually 2ary to?
Pulmonary arterial thromboembolus
What is a ‘bleb’ in the lung?
In the lungs, a bleb is a collection of air within the layers of the visceral pleura.
Lung bleb vs bulla?
If blebs become larger or come together to form a larger cyst, they are called bulla.
Which lung condition are bullae common complications of? What is the danger of this?
A giant bulla is a complication of emphysema. In areas of the lung completely damaged by the disease, air pockets can develop. These areas threaten the patient’s health not only because of the underlying emphysema. As an air pocket—a bulla—grows, it takes up space in the chest cavity and can encroach on the lungs.
Emphysema can lead to pleurisy. What is this usually 2ary to?
Ruptured bullae
Can neoplasms lead to pleurisy?
Yes
When would pleurisy be therapeutically induced?
Pleurodesis - talc is put into the pleural cavity to induce inflammation, causing the pleural cavity to seal up, preventing fluid (pleural effusions) or air (pneumothoraxes) from continually building up around your lungs.
What can iatrogenic pleurisy occur?
- Radiotherapy to the thorax
- Immune reactions to a drugs
Signs and symptoms of pleural inflammation if there is no associated pleural effusion?
- Symptom - Pleuritic chest pain, a sharp localised pain exacerbated by breathing
- Sign - Auscultation of a pleural rub during breathing
What is pleuritic chest pain?
Chest pain exacerbated by deep breathing, coughing, sneezing, or laughing. The pain is sudden and intense sharp, stabbing, or burning in nature.
What is a pleural rub? What is it caused by?
An adventitious breath sound heard on auscultation of the lung. The pleural rub sound results from the movement of inflamed and roughened pleural surfaces against one another during movement of the chest wall.
What is pleural fibrosis?
Pleural fibrosis and calcification are thickening and stiffening of the pleura
What 2 major factors predispose to pleural fibrosis?
- Pleural inflammation
- Asbestos exposure
What are the 2 types of asbestos associated pleural fibrosis?
- Parietal pleural fibrous plaques; related to low level asbestos exposure
- Diffuse pleural fibrosis; related to high level asbestos exposure
What are the effects of widespread thick pleural fibrosis? What symptom does this lead to?
Can prevent normal expansion and compression of the lung during respiration causing breathlessness. Fibrous adhesions can wholly or partly obliterate the pleural cavity.
What is pleural decortication?
Removal of the fibrous tissue to improve the expansion and compression of the lung during respiration
What are parietal pleural fibrous plaques associated with?
Associated with low level asbestos dust exposure
How do parietal pleural fibrous plaques present?
- Asymptomatic
- May be visible on chest radiographs
- Dense poorly cellular collagen
Are parietal pleural fibrous plaques a serious disease?
It is not a UK Government Prescribed Occupational Disease therefore it is not eligible for Industrial Injuries Disablement Benefit
What is diffuse pleural fibrosis associated with?
Associated with high level asbestos dust exposure
How does diffuse pleural fibrosis typically present?
- Usually bilateral
- Dense cellular collagen not extending into interlobar fissures
- Prevents normal expansion and compression of the lung during breathing causing breathlessness
Is diffuse pleural fibrosis recognised as a UK Government Prescribed Occupational disease?
Yes - is eligible for Industrial Injuries Disablement Benefit
What are the 6 major pathological fluids that can occur in the pleural cavities? What are the names of the disease that each causes?
- Serous fluid –> pleural effusion
- Pus –> empyema or pyothorax
- Blood –> haemothorax
- Bile –> cholethorax
- Lymph –> chylothorax
- Gas –> pneumothorax
What is empyema/pyothorax usually 2ary to?
Pneumonia
What is haemothorax usually 2ary to?
Usually traumatic or a ruptured thoracic aortic aneurysm
What is a chylothorax usually 2ary to?
Traumatic
If a patient with a pleural effusion has an CXR taken standing up, where does the fluid tend to accumulate?
At the bottom of the lung(s) - is a horizontal line between the fluid and the lung above
What are the 2 types of pleural effusion?
- Transudate
- Exudate
What are the 2 causes of a transudative pleural effusion?
- Increased pressure in blood vessles (high vascular hydrostatic pressure)
- Low protein blood count (low capillary oncotic/colloid osmotic pressure)
What is the plasma oncotic pressure?
The plasma oncotic pressure is that part of the total osmotic pressure of the plasma that is due to impermeant proteins.
Reduction in plasma proteins = reduction in oncotic pressure
How can a high vascular hydrostatic pressure lead to a transudative pleural effusion?
This pressure drives fluid out of the capillary (i.e., filtration) –> Forces fluid out of the vessels
What are the 2 major causes of a high vascular hydrostatic pressure (leading to a transudative pleural effusion)?
- Left ventricular failure
- Renal failure
How can a low capillary oncotic pressure lead to a transudative pleural effusion?
Filtering of fluid out of vessels (and into extravascular space) leads to an increase in protein concentration inside the vessel
What is the capillary plasma oncotic pressure determined by?
Plasma proteins that are relatively impermeable –> ALBUMIN
Which protein generates about 70% of the oncotic pressure?
Albumin
What is the major cause of low capillary oncotic (colloid osmotic) pressure?
Hypoalbuminaemia
What can cause hypoalbuminaemia?
Hepatic cirrhosis, nephrotic syndrome
What are the 2 major causes of exudative pleural effusion?
- Inflammation with/without infection
- Neoplasms either primary or secondary; can damage vessel walls and lead to exudation of fluid
How can you distinguish a transudative from an exudative pleural effusion?
If the patient’s serum total protein is normal and the pleural fluid protein is less than 25g/L the fluid is a transudate.
If the pleural fluid protein is greater than 35g/L the fluid is an exudate.
Symptoms of pleural effusion?
- Breathlessness
- Little/no pleuritic pain
Why can a pleural effusion lead to breathlessness?
Effusion compresses the lung
Why does a pleural effusion cause little/no pleuritc pain?
The visceral and parietal pleura are not in contact
Describe the percussion and auscultation sounds in a pleural effusion
Percussion; dull (due to collection of fluid)
Auscultation; reduced breath sounds (no air going in and out of area)
Which imaging should be done to confirm diagnosis of pleural effusion?
US, chest radiograph, CT
How are pleural effusions treated?
- Treat the breathlessness –> remove the fluid
- Aspiration with a needle and syringe, ultrasound guided
- Reaspirate if the fluid reaccumulates
- Identify and treat the underlying cause
- Local:
- Pleural fluid for cytology, microbiology, & biochemistry
- Pleural biopsy
- Systemic: investigate the systemic causes of pleural effusions
- Local:
For drainage of recurrent pleural effusions, what should be considered?
- consider a temporary or permanent pleural drain
- consider pleurodesis to obliterate the pleural cavity
What is the danger of a permanent pleural drain?
Infection
What are the 2 types of a pneumothorax?
- Open
- Closed
What is an open pneumothorax?
- A chest wall perforation usually traumatic – a “sucking chest wound” – connects the body surface to the pleural cavity
- External air is drawn into the pleural cavity during inspiration, reducing potential lung expansion
What is a closed pneumothorax?
- A lung perforation, usually not traumatic, connects the lung air spaces to the pleural cavity
- Lung air is drawn into the pleural cavity during inspiration, reducing potential lung expansion
What is connected to the pleural cavity in a;
a) open pneumothorax
b) closed pneumothorax
a) body surface
b) lung air spaces
What type of pneumothorax would a ruptured emphysematous bullae cause?
Closed
What are the common causes of a closed pneumothorax?
- Ruptured emphysematous bullae
- Common inflammatory lung diseases
- Asthma, pneumonia, tuberculosis, cystic fibrosis
- Traumatic – lung tears from fractured ribs
- Iatrogenic
- Mechanical ventilation at high pressures
- Lung and pleural biopsy procedures
Open vs closed pneumothorax?
Pneumothorax is classified as open or closed and according to the causative mechanism. Open pneumothorax results from a penetrating thoracic injury that permits entry of air into the chest, while closed pneumothorax is the accumulation of air originating from the respiratory system within the pleural space.
What type of pneumothorax would a lung tear from a fractured rib caused?
Closed
What are 2 rarer causes of a closed pneumothorax?
- Some rare cystic lung diseases – Langerhans’ cell histiocytosis, lymphangioleiomyomatosis
- Catamenial due to pleural endometriosis
What is catamenial pneumothorax?
Catamenial pneumothorax is a pneumothorax occurring in conjunction with menstrual periods (catamenial refers to menstruation), and or during ovulation, believed to be caused primarily by endometriosis of the pleura.
What is a tension pneumothorax?
The perforation into the pleural cavity in an open or a closed pnemothorax can be valvular, allowing air into the cavity during inspiration but not out during expiration. This causes the pressure in the pneumothorax to rise above atmospheric pressure.
In a tension pneumothorax, if the pressure in the pneumothorax rises above atmospheric pressure, what can happen?
This can compress mediastinal structures including the vena cava and heart and move the mediastinum compressing the contralateral lung.
A tension pneumothorax is potentially fatal and requires urgent treatment!
Symptoms of a pneumothorax?
- Small ones may be asymptomatic
- Breathlessness
- Pleuritic chest pain (as pleura damaged)
Signs of a pneumothorax? What is the percussion and auscultation?
Signs related to impaired respiratory function:
- Cyanosis
- Tachycardia
- Contralateral tracheal deviation in tension pneumothorax
- Percussion – hyperresonant
- Auscultation – reduced breath sounds
Investigations to support the diagnosis of a pneumothorax?
- Imaging – ultrasound, chest radiograph, CT
- Symptomatic pneumothoraces are often initially treated without further investigation
Treatment of small pneumothorax?
may resolve spontaneously
Immediate treatment of a tension pneumothorax?
A tension pneumothorax can be decompressed as an emergency procedure using a needle inserted via an intercostal space
Treatment of an open pneumothorax?
The penetrating chest wound causing it can be covered with an occlusive adhesive dressing that may incorporate a valve to allow air out but not in.
Standard treatment for any pneumothorax?
For any pneumothorax a chest drain tube can be inserted incorporating a valve to allow air out but not in while the pneumothorax resolves.
•For recurrent pneumothoraces, what is usually considered?
Pleurodesis
What are the 2 types of 1ary pleural neoplasms?
- Benign/low grade malignant (uncommon/rare)
- Malignant
What is the most common malignant primary pleural neoplasm?
Malignant mesothelioma
Malignant pleural neoplasms can also be secondary. Where do these commonly metastasise from?
- Carcinomas – breast, lung, others (common)
- Others – lymphoma, melanoma, others
What is a malignant mesothelioma?
A neoplasm of the mesothelial cells that line serous cavities; pleura, peritoneum, pericardium, tunica vaginalis
What are 92% of malignant mesotheliomas?
Pleural (only 8% are peritoneal)
Incidence in men vs women of malignant mesotheliomas?
- Both are commoner in men
- Peritoneal mesotheliomas affect a higher proportion of women, have a higher proportion of low grade type and are less strongly associated with asbestos dust exposure
Where do pleural malignant mesotheliomas tend to metastasise to?
NOT widely - mainly to other pleural cavity and the peritoneal cavity
Symptoms of malignant mesothelioma?
- CAN CAUSE PLEURAL EFFUSION
- chest pain.
- shortness of breath.
- fatigue (extreme tiredness)
- a high temperature (fever) and sweating, particularly at night.
- a persistent cough.
- loss of appetite and unexplained weight loss.
- clubbed (swollen) fingertips.
Why can malignant mesotheliomas be difficult to biopsy?
The tumour can be difficult to identify on imaging and therefore it is difficult to target biopsies at it
Instead of biopsies, how can an early tissue diagnosis of a malignant mesothelioma be made?
A small tumour can produce a large pleural effusion –> malignant cells may be shed into the effusion therefore effusion cytology may allow an early tissue diagnosis to be made
What is a malignant pleural mesothelioma associated with?
Asbestos exposure
Malignant mesothelioma histology?
- Mixed tubulopapillary epithelioid & spindle cell sarcomatioid morphology
- Can be either type alone
- Can be poorly cellular - “desmoplatic”
Lung cancer vs mesothelioma?
While malignant mesothelioma is cancerous, it is not a form of lung cancer. Lung cancer develops inside the lungs, while mesothelioma causes tumors of the pleural tissue that surrounds the outside of the lungs, diaphragm and chest cavity.
What is the main morphological differential diagnosis for malignant mesothelioma?
malignant mesothelioma or non-small carcinoma (e.g. adenocarcinoma)
How can you differentiate between adenocarcinoma and mesothelioma?
Immunostaining:
- Uses antibodies linked to a dye to identify antigens is cells
- Mesothelial cells and epithelial cells tend to express different antigens allowing them to be differentiated from each other
What is the major cause of mesothelioma?
Asbestos exposure:
- The exposure can be quite low level
- Mesothelioma develops 15 years to over 60 years after exposure
- The risk increases with cumulative exposure level and time from exposure
Also linked to radiation exposure (e.g. thoracic irradation)
Which gene can be implicated in mesotheliomas?
BAP1 (BRCA1-associated protein 1) mutations
What are germline BAP1 mutations associated with?
Familial cancer syndrome; uveal melanomas and mesotheliomas
What is BAP1?
BAP1 is a nuclear protein encoded by the BAP1 tumour-suppressor gene located on chromosome 3
What is asbestos?
Asbestos is a naturally occurring fibre (fiborus metal silicates) that was widely used in construction and other industries until the late 1990s:
- Amphibole - blue asbestos (crocidolite), brown asbestos (amosite)
- Serpentine - white asbestos (chrysotile)
How can asbestos exposure lead to cancer?
- When inhaled some become coated with mucopolysacharides containing iron to form asbestos bodies
- Over many years, the fibers can cause enough genetic and cellular damage to cause lung cells to turn cancerous.
What are the 2 major types of asbestos?
- Amphiboles;
- blue asbestos (crocidolite)
- brown asbestos (amosite)
- Serpentines
- white asbestos (chrysotile)
Which type of asbestos is most oncogenic?
Amphiboles
How oncogenic is chryostile (a type of serpentine asbestos)?
Chrysotile is less oncogenic and is more readily cleared from the lungs
What is ‘Erionite’?
Erionite is a fibrous zeolite mineral that has a fibre structure similar to asbestos. It is used as a building material in areas of Cappadocia, Turkey where there is a very high incidence of mesothelioma occurring in young people.
What was asbestos used for?
A fire-proof material widely used in commercial and domestic buildings and in shipbuilding from the 1940s to the 1990s
What is asbestosis?
- Asbestosis is a usual interstitial pneumonia-like progressive pulmonary interstitial fibrosis caused by high level exposure to asbestos dust
- Fibrosis of the alveolar walls impairs both gas exchange and lung expansion and contraction during breathing
Is asbestos a UK Government Prescribed Occupational Disease?
Yes - eligible for Industrial Injuries Disablement Benefit
Asbestos-related diseases summary:
-
Pleural
- Pleural effusion
- Parietal pleural fibrous plaques
- Diffuse pleural fibrosis
- Malignant mesothelioma - 2567 UK deaths in 2014
-
Lung
- Asbestosis - 431 UK deaths in 2014
- Lung carcinoma – about 2000 UK deaths in 2014
-
Skin
- Asbestos corns – benign hyperkeratotic wart-like skin lesions
What skin condition can asbestos exposure lead to?
Asbestos corns - Asbestos fibres may penetrate the skin and cause benign lesions around the implanted fibres, such as warts and corns
What is a pleural rub sound?
A pleural friction rub is an adventitious breath sound heard on auscultation of the lung. The pleural rub sound results from the movement of inflamed and roughened pleural surfaces against one another during movement of the chest wall.
