Parietal pleura and extrapleural space in chronic tuberculous empyema: CT-pathologic correlation

PURPOSE: The purpose of this work was to describe CT findings of the parietal pleura and extrapleural space in patients with chronic tuberculous empyema and to compare them with histopathologic findings following decortication. METHOD: Chest CT scans obtained from 13 patients with chronic tuberculous empyema who underwent decortication were retrospectively reviewed. All patients were men from 18 to 67 years old (mean 42 years old). CT findings of the parietal pleura and extrapleural space were correlated with histopathologic findings in all patients. RESULTS: Histopathologically, the enhanced parietal pleural peel on CT was fibrous collagenous tissue, and a low attenuated layer with 2 mm thickness within the parietal pleural peel (n = 2) was either a layer of histiocytes or caseation necrosis. The extrapleural space seen as an intermediate attenuation in six patients on CT was the proliferation of vessels, inflammatory cells, and granulomas in loose collagen background. The linear soft tissue attenuation interrupting the extrapleural fat (n = 5) on CT was a collagenous fibrous layer with proliferation of vessels and inflammatory cells. CONCLUSION: A layer of low attenuation in the parietal pleural peel may be due to different episodes of infection. The extrapleural space with intermediate attenuation may indicate ongoing inflammation. Linear soft tissue attenuation interrupting the extrapleural fat represents a fibrous layer rather than the subcostalis muscle.