Pathology of the pleura and pleural spaces

Question 1

What is pleural effusion?

Answer 1

Accumulation of fluid in the pleural space (normal <15ml);
* Manifestation of both primary and secondary pleural diseases

Question 2

What causes pleural effusion?

Answer 2

increased hydrostatic pressure (e.g. congestive heart failure),
* increased vascular permeability (e.g. pneumonia),
* decreased osmotic pressure (e.g. nephrotic syndrome),
* increased intrapleural negative pressure (e.g. atelectasis) or
* decreased lymphatic drainage (e.g. mediastinal carcinomatosis)

Question 3

Describe inflammatory pleural effusion and its cause

Answer 3

Serous, serofibrinous and fibrinous pleuritis:
Aetiology :usually due to inflammation of the underlying lung
o Tuberculosis, pneumonia, lung infarction
o Systemic conditions e.g. Rheumatoid arthritis, uraemia, metastatic pleural involvement, radiotherapy for
lung/pleural tumours

Question 4

How do infl. effusions resolve?

Answer 4

Usually resolves with resorption of fluid +/- organisation of the fibrinous component

Question 5

What is hemorrhagic pleuritis?

Answer 5

Haemorrhagic pleuritis: Sanguineous( resembling
or containing blood).
inflammatory exudate (different from haemothorax); Hemorrhagic pleural effusion is defined as an erythrocyte
count greater than 100,000 cells/µl.2
uncommon and tumour involvement of the pleura must be excluded

Question 6

What is an empyema

Answer 6

Empyema (purulent pleural exudate):
due to bacterial or mycotic seeding of the pleural
space (e.g. spread from intrapulmonary infections or more distant sources)
o Volume is usually small and the pus gets walled off
by fibrosis; usually organizes into dense, tough fibrous adhesions that obliterate the pleural space or encases the lung (empyema peel) and can restrict lung expansion

Question 7

Explain 3 types of non-infl. effusions

Answer 7

• Hydrothorax (serous fluid): Most commonly due to heart failure; also seen in other systemic
  conditions associated with generalized oedema e.g. renal failure, liver cirrhosis
• Haemothorax (blood): is a pleural fluid with blood hematocrit ratio greater than 50% . Compare to
  haemorrhagic effusion .Usually due to trauma, surgery or rupture of aortic aneurysm
• Chylothorax (lymph fluid): Milky white appearance due to finely emulsified fats. Usually due to thoracic
  duct trauma or obstruction of a major lymphatic duct (usually by malignancy)

Question 8

List 3 types of pneumothorax

Answer 8

Spontaneous pneumothorax
Traumatic pneumothorax
Tension pneumothorax

Question 9

What is the most common causes of tumors in the pleura?

Answer 9

econdary involvement of the pleura by metastases is more common than primary pleural tumours,
usually from lung or breast primary tumours and often producing a serous or serosanguineous pleural
effusio

Question 10

What is malignant mesothelioma

Answer 10

Malignant tumour arising from mesothelial cells lining the serous cavities

Question 11

What are the risk factors of malignant mesothelioma?

Answer 11

Asbestos exposure (long latent period; risk is not magnified by smoking, unlike
asbestos-related lung carcinomas)

Question 12

Clinical findings of malignant mesothelioma

Answer 12

Presents with chest pain, dyspnoea, recurrent pleural effusions. Generally poor
prognosis

Question 13

Gross appearance of malignant mesothelioma

Answer 13

Diffuse soft greyish-pink tumour arising from either visceral or parietal pleura; usually associated with extensive pleural effusion and direct invasion of thoracic structures