A pulmonary pseudotumour is no more than 'something' which mimics a tumour. Most frequently the term is used to denote focal collections of fluid trapped in the pleural fissures. Other entities which have been described with the term pseudotumours include:
- round atelectasis
- pulmonary inflammatory pseudotumour 1
- epicardial fat pad 2
- fat within pleural fissures 2
- mucoid impaction (e.g. finger in glove sign) 3
- calcifying fibrous pseudotumour (CFPT) of lung 4
For the purpose of this article, the term pulmonary pseudotumour will be used to signify focal collections of pleural fluid, although the term is clearly not a very useful one, and care should be taken when using it.
The demographics reflect those of patients who are prone to pleural effusions. A typical group would be those with congestive cardiac failure (thus the term vanishing pseudotumour of congestive cardiac failure).
The amounts of fluid involved are small and are asymptomatic. They are typically found incidentally when chest x-rays are performed for another indication; frequently assessment of pleural oedema in a patient with congestive cardiac failure.
Pseudotumours cause most confusion on chest radiographs where they appear as a solitary pulmonary mass. Knowledge of the normal location of the pleural fissure helps to make one suspicious of the diagnosis. These opacities are typically elongated along the direction of the fissure and may have tapering ends.
Obtaining a lateral projection is often very helpful.
Features of congestive cardiac failure are frequently present.
CT is usually not required, unless the diagnosis has not been suspected or the opacity fails to resolve once pulmonary oedema has been treated.
Appearances on CT are similar to those on CXR: the mass is located along a pleural fissure with tapering ends, and is of fluid attenuation.
Care must be taken in considering the potential for accessory pleural fissures.
Treatment and prognosis
No direct treatment is required, and management of the underlying cause of pleural fluid (usually heart failure) leads to resolution of opacity.
The differential is very broad and encompasses :
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