PURPOSE: To define the CT findings of inflammatory pseudotumor of the lung, and determine pathologiccorrelation. MATERIALS AND METHODS: We retrospectively analyzed the CT scans of seven patients withpathologically-proven (surgery:n=6; automated gun biopsy:n=1) inflammatory pseudotumor of the lung. Postcontrastscans were obtained in six cases, while one underwent only precontrast scanning. In all cases, these resultscorrelated with pathologic findings. RESULTS: In five cases, CT showed that irregular, spiculated nodules ormasses contacted with the pleura; in one, a well-defined nodule contacted with the fissure; and in one, there wasconsolidation. On postcontrast CT images, all six cases showed enhancement, with a central, low-density component. In four cases, ground-glass opacity surrounding the lesion was identified, and in three focal pleural thickeningadjacent to the lesion was noted. The predominant pathologic composition of the enhanced portions of the lesion,as seen on CT, was chronic inflammatory or spindle cells, and the angiogenesis of small vessels was also noted.Non-enhanced, central, low-density areas were accounted for by hemorrhaging, necrosis and the focal aggregation ofacute and chronic inflammatory cells. Surrounding gound-glass opacity corresponded pathologically to organizingpneumonia, cellular infiltration along the alveolar wall, and alveolar collapse. CONCLUSION: The CT features ofinlammatory pseudotumor of the lung were mainly peripheral irregular, spiculated nodule or mass, withcontrast-enhancement and a central low-density component, combined with surrounding ground-glass opacity. Allthese findings correlated well with pathologic findings.