High resolution computed tomography in sarcoidosis: typical findings.

Sarcoidosis is a systemic disorder of unknown cause in which noncaseating granulomas occur. Granulomas are formed in lymphatic or perilymphatic distribution, along lymphatics and in peribronchovascular interstitium. In some cases the granulomas are formed in interlobular septa or subpleural interstitium. Nodular interstitial densities in parahilar lung regions are very typical of sarcoidosis, especially with coexistent hilar lymphadenopathy. In HRCT the appearance of pulmonary sarcoidosis may vary, masquerading many other diffuse interstitiallung diseases. The aim of the study is the evaluation of the typical findings for sarcoidosis in HRCT, and assessment of their value in differential diagnosis. The most typical HRCT finding in patients with sarcoidosis are small nodules. They are predominantly distributed adjacent to peribronchovascular and subpleural interstitium. Thickenings of peribronchovascular and septal interstitium are also often seen in sarcoidosis. Ground glass opacities are seen in early stages of sarcoidosis. Conglomerates of masses and large nodules may also be seen in advanced diseases, with traction bronchiectases and honeycombing as a result of fibrosis.