Pseudotumor of Lung
Vanishing Tumor

General Considerations

• Sharply marginated collection of pleural fluid contained either within an interlobar pulmonary fissure or in a subpleural location adjacent to a fissure
• Result from transudation from the pulmonary vascular space
• Commonly manifest as incidental radiographic findings in patients with congestive heart failure
• Other causes of transudates include
• Hypoalbuminemia
• Renal insufficiency
• Patients who develop pseudotumors tend to develop them repeatedly when the underlying condition causing the transudate (like CHF) returns
• Pseudotumors may be erroneously diagnosed as parenchymal lung nodules or masses
• Presence of an interlobar pleural effusion does not always correspond to the severity of the left heart failure

Imaging findings

• Lenticular  or biconvex contour
• Located along the course of interlobar fissures
• Most occur in the minor (horizontal) fissure (more than 75%) and are seen on both the frontal and lateral radiograph
• Those that occur in the oblique or major fissure may only be seen on the lateral view well
• Infrequently, they occur in the horizontal and oblique fissures simultaneously
• Most are less than 4 cm in size

Management

• The underlying condition is managed
• Typically an incidental finding that has minimal impact on patient management
• Occasionally, it may be the only sign of cardiac decompensation  

 
Pseudotumor of Lung. Frontal and lateral views of the chest demonstrate a lemon-shaped soft-tissue density corresponding to the location of the minor fissure on both views (white arrows). This is a classic appearance for a pseudotumor of the lung.

Massive Pulmonary Pseudotumor:  Brian M. Haus, BA; Paul Stark, MD; Scott L. Shofer, MD and Ware G. Kuschner, MD, FCCP Chest. 2003;124:758-760