CT and pathological correlation of pulmonary sarcoidosis

In CT the presence of mediastinal or hilar lymphadenopathies and thickened bronchovascular bundles are landmarks for the diagnosis of pulmonary sarcoidosis. The major CT findings for parenchymal involvement are thickened bronchovascular bundles, large parenchymal nodules, pleural or subpleural nodules, ground-glass opacities, local lung volume loss (distortion of the lung parenchyma), and microscopic and macroscopic honeycombing. The thickened bronchovascular bundles correspond histologically to granulomas, either with or without perigranulomatous fibrosis in the connective tissue sheath around the pulmonary vessels and airways. Conglomerate granulomas are represented on CT by high-attenuation nodules, and the ground-glass opacities are caused by the summation of a number of small granulomas in the interstitium.