The term pulmonary pseudotumor may be used to describe a well-demarcated interlobar pleural effusion. Pseudotumors are located within pulmonary fissures and are commonly associated with congestive heart failure and other processes that cause transudative pleural effusions. Pseudotumors are typically diagnosed presumptively on chest radiographs based on their lenticular configuration. We report a case of a massive pseudotumor opacifying one third of the right hemithorax on a frontal radiograph. CT scan of the chest showed a loculated effusion within the oblique fissure measuring 10 x 5 cm. The Hounsfield unit characteristic of the effusion was similar to that of freely layering liquid in the contralateral hemithorax that was shown to be a transudate. The pseudotumor resolved with medical management over 8 weeks. This case proves that even a massive pulmonary pseudotumor will resolve with conservative management.