HRCT in miliary lung disease

Purpose: To analyze high resolution CT (HRCT) features of a miliary pattern in different diseases. Material and Methods: Eight HRCT studies with a miliary lung pattern were r etrospectively reviewed with the diagnoses tuberculosis (n=3), Candida albi cans (n=1), sarcoidosis (n=3), and metastatic adenocarcinoma (n=1). Results. In all cases, HRCT showed diffusely disseminated nodules up to 3 m m. In 2 cases of tuberculosis and 1 of sarcoidosis, the lesions predominate d in the upper/middle lung zones. In the case of metastatic adenocarcinoma the nodules were more sparse in the lung periphery while in I case of sarco idosis, HRCT revealed a predominance of the lesions in the outer third of t he lungs. Cyst-like lesions of 1-2 mm were observed in 2/3 cases of tubercu losis and in metastatic adenocarcinoma. Notably thickened interlobular sept a and interlobar fissures were each seen in 2/3 cases of sarcoidosis. In ge neral, a random relationship of miliary nodules to secondary lobular struct ures and bronchovascular bundles was observed, despite the co-existence of centrilobular, subpleural and paraseptal nodules. Conclusion: HRCT features that potentially contribute in making a different ial diagnosis are: a) A peripheral distribution of nodules, an increased nu mber of thickened interlobular septae, and a notable thickening of interlob ar fissures, all of which are indicative of sarcoidosis; and b) Multiple cy st-like lesions which should direct attention to tuberculous or metastatic origin. The predominance of miliary nodules in relation to cephalocaudal ax is, their margin and size are not helpful features to the differential diag nosis of diseases presenting a miliary pattern.