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Imaging Sciences Interesting Cases

Case 224

Trushar Sarang, MD

Clinical Presentation: Patient is a 69-year-old male with dyspnea.

Imaging Findings: Large, right mid-lung zone rounded opacity.
Figure 1: There is a large round opacity projecting over the right mid-lung zone. There are also bilateral pleural effusions and emphysematous changes at the apices.
Figure 2: CT demonstrates fluid in the minor fissure with HU approximately equal to 1.
Figure 3: After treatment for CHF and placement of a cardiac pacemaker, the pleural effusions and loculated fluid in the minor fissure have decreased.

Diagnosis: Pseudotumor

Discussion: Pseudotumor on chest radiographs result from pleural effusions that subsequently loculate in the pleural fissures. They often occur with exudative pleural effusions, but can occur with transudative effusions as well. Common causes include hypoalbuminemia, renal insufficiency, and congestive heart failure (as in this case).

The pseudomass is usually lenticular in shape with sharp margins and usually less than 4 cm in size. Typically, collections in the minor fissure are well circumscribed on both the frontal and lateral views because the surface of the collection is parallel to the x-ray beam on both projections. Collections in the anterior, posterior, and lateral pleural spaces may appear well circumscribed in one projection and ill-defined in another based on the angle of projection with the fluid margin. Parenchymal masses will appear similar in different projections. Case reports of massive pseudotumors have been reported. Over 75% involve the minor fissure.

Misdiagnosis may result in unnecessary patient anxiety, antibiotics, invasive procedures such as biopsy, and other costly imaging tests. Management is conservative with treatment of the underlying condition.

References:

  1. Webb WR, Higgins CB. Thoracic Imaging: Pulmonary and Cardiovascular Radiology. Lippincott Williams and Wilkins. Philadelphia, 2005.
  2. Haus BM, Stark P, Shofer SL, Kuschner WG. Massive pulmonary pseudotumor. Chest. 2003 Aug;124(2):758-60. [PubMed]