Pulmonary tuberculosis: another disease showing clusters of small nodules.

Abstract

Pulmonary sarcoidosis was recently reported to show the "sarcoid galaxy" sign, indicating large pulmonary nodules composed of coalescent small nodules. The purpose of this study was to review cases of pulmonary tuberculosis showing CT features indistinguishable from the sarcoid galaxy sign. Large nodules arising from the coalescence of small nodules may be seen in active tuberculosis and in sarcoidosis. The CT finding was termed "clusters of small nodules" instead of the "sarcoid galaxy sign" in this article. A single cluster of small nodules, clusters of small nodules in the superior segment of the lower lobe, or clusters of small nodules not associated with lymphadenopathy or associated with tree-in-bud lesions would favor the diagnosis of active pulmonary tuberculosis rather than pulmonary sarcoidosis.