Pleural pseudotumours refer to encysted focal pleural fluid collections within a lung fissure that may simulate a mass.
On this page:
Pathology
Normally there is a similar retractile force applied to the entire pleural space by adjacent lung. When there is a pleural effusion, the elastic recoil of the lung causes each lobe to retract toward the hilum. This can widen the fissures, drawing fluid into them even in non-dependent locations.
Location
The middle lobe (being the smallest lobe), has the greatest tendency to retract, and therefore the horizontal fissure is more prone to developing a pseudotumour.
Pseudotumours almost always occur with transudates: caused by congestive heart failure, cirrhosis, or renal insufficiency.
Radiographic features
Plain radiograph
Lenticular or biconvex opacity along an expected course of a fissure. As with other pleural based pathologies, one of the borders of the pseudomass may be well defined while the other may not. A concurrent dependent pleural effusion aids recognition of a pleural pseudotumour.
CT
May be useful in difficult cases in which the fluid is situated along the edge of the lung, is difficult to relate to a fissure, or has an unusual shape, leading to misinterpretation as a pleural mass.
Treatment and prognosis
They usually resolve after therapy with diuretic agents or treatment of the underlying predisposing condition.