Conditions affecting the pleura

The causes and symptoms of pleural disease are discussed by Dr Peter Davies

While there are specific pleural diseases, in most cases the pleural involvement is a symptom of an underlying lung disease. The pathophysiology of pleural disease is best understood by thinking of the effects of the pathological processes on the contents of the pleural space.

While most of the management of more serious pleural disease is done in hospital, GPs should be aware of the features that will help decide the initial diagnosis and management.

Acute pleuritic pain

Acute pleuritic pain is a common presenting symptom in primary care. It is a sharp stabbing pain, worse on inspiration, on cough and/or on movement. It is usually well localised and away from the centre of the chest. It may be described by the patient as ‘catching my breath'. The context usually points to the diagnosis. A rib injury, a shingles rash or a history of accompanying URTI may provide an explanation.

A history of cough and phlegm points to pleural involvement in an underlying pneumonia. Sometimes pleural pain may be the first symptom of a pneumonia.

The speed of onset is important. Acute onset of the pleuritic pain might reflect serious pathology, especially if associated with haemoptysis.

If there is a recognisable viral trigger, a clear history of chest infection, or an obvious mechanical problem it is safe to treat the patient in primary care. If there is suspicion of more severe illness such as pneumonia, pulmonary embolus or pneumothorax then further referral is needed.

Pneumothorax

Pneumothorax is the presence of air in the pleural space. It can occur spontaneously or as a complication of an underlying lung disease. Patients who are tall and thin are more at risk of pneumothorax. It can also occur as a consequence of medical interventions such as central line insertion.

The presentation is variable and it is an easy diagnosis to miss. Sudden onset of pleuritic pain and breathlessness is one presentation. A healthy, fit person may tolerate a small pneumothorax very well and not appear unduly breathless or distressed.

Abnormal physical signs such as hyperresonance on percussion or absent breath sounds over part of the lung are not always easy to detect.

Tracheal deviation and displaced apex beat are worth checking for, especially if there is severe breathlessness and the possibility of tension pneumothorax.

If pneumothorax is suspected a chest X-ray should be arranged. A small pneumothorax may resolve spontaneously but larger pneumothoraces need to be either aspirated or drained.

If the pneumothorax recurs then consideration will be given to medical or surgical pleurodesis.

Pleural effusion

Pleural effusions can be classified into transudates - protein content less than 30g/l - and exudates - protein content over 30g/l.

Transudates may be caused by congestive heart failure or constrictive pericarditis, or hypoproteinaemic states such as nephrotic syndrome and liver failure.

Exudates may be caused by infections including pneumonia and tuberculosis, inflammatory conditions such as pancreatitis or rheumatoid arthritis, and cancers, whether primary, from lung or secondary from breast, lymphoma or elsewhere.

Mesothelioma can also cause a pleural effusion.

Pleural effusions build gradually and the symptoms and signs generally develop slowly. Small effusions will probably be asymptomatic.

As the effusion increases the symptoms of breathlessness develop, on exercise and at rest. Some effusions can present with pain. A chest X-ray and prompt investigations at the hospital are essential.

If a malignant effusion is suspected this is one of the indications to use the two week cancer rule for an urgent referral. If breathlessness is severe then admission is justified.

Haemothorax

Haemothorax is most likely to occur in the context of trauma and may well be combined with a pneumothorax.

The trauma is usually a penetrating chest wound, either by criminal assault or after medical interventions such as central line insertion.

The GP should then admit the patient to hospital for a chest drain.

Pleural plaques

Pleural plaques are a consequence of asbestos exposure. They cause no harm to the patient or their lung function. They are found incidentally on a chest X-ray and they indicate past asbestos exposure. They do not predispose to the development of mesothelioma.

Mesothelioma

Mesothelioma is a slow growing tumour that presents insidiously. It may be up to 40 years from the time of exposure to asbestos to the time of presentation and diagnosis.

The tumour spreads over the surface of the pleura and so encases and restricts the movement of the lung.

The presentation of the tumour is with gradual build up of breathlessness, pain or a pleural effusion. Treatment is palliative, but some surgical options are showing promise in selected patients.

Median survival is under one year. The illness is often associated with severe pain and breathlessness as it progresses.

  • Dr Davies is a GP in Illingworth, Halifax
KEY POINTS
  
  • In most cases pleural involvement is a symptom of an underlying lung disease.
  • A diagnosis can be made in the context of the patient's history.
  • A chest X-ray should be taken if there is suspected pleural involvement.
  • Pleural symptoms could be an indication of pneumonia, pulmonary embolus or more serious conditions such as malignancy.
  • Other serious conditions may present with pleural effusion, for example tuberculosis, pancreatitis, congestive heart failure or constrictive pericarditis.
  • The presence of pleural plaques do not necessary mean the development of mesothelioma.

 

 REFERENCES
  • Warrell D et al. Oxford Textbook of Medicine. Chapter 17.43 and 17.170. Oxford University Press, Oxford. Accessed at: www.doctors.net.uk/library
  • Treasure T et al. Radical surgery for mesothelioma. BMJ 2004; 328: 327-8

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