Galaxy sign (lungs)
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At the time the article was created Frank Gaillard had no recorded disclosures.View Frank Gaillard's current disclosures
At the time the article was last revised Luu Hanh had no recorded disclosures.View Luu Hanh's current disclosures
The so-called galaxy sign, initially described as the sarcoid galaxy, represents a coalescent granuloma seen in a minority of patients with pulmonary sarcoidosis 1. The same appearance can be seen in tuberculosis 2,3. In other words, it represents a mass-like region composed of numerous smaller granulomas. The appearance of a central core with peripheral nodules is reminiscent of a globular cluster or galaxy.
Central cavitation does occur and the lesions may be surrounded by ground-glass opacity 4. The latter is thought to represent extensive interstitial sarcoid granulomas below the resolution of HRCT rather than alveolitis or hemorrhage 1.
- 1. Nakatsu M, Hatabu H, Morikawa K et-al. Large coalescent parenchymal nodules in pulmonary sarcoidosis: "sarcoid galaxy" sign. AJR Am J Roentgenol. 2002;178 (6): 1389-93. AJR Am J Roentgenol (full text) [pubmed citation]
- 2. Heo JN, Choi YW, Jeon SC et-al. Pulmonary tuberculosis: another disease showing clusters of small nodules. AJR Am J Roentgenol. 2005;184 (2): 639-42. AJR Am J Roentgenol (full text) [pubmed citation]
- 3. Aikins A, Kanne JP, Chung JH. Galaxy sign. J Thorac Imaging. 2012;27 (6): W164. doi:10.1097/RTI.0b013e31826b7e6f - Pubmed citation
- 4. Chiarenza A, Esposto Ultimo L, Falsaperla D, Travali M, Foti PV, Torrisi SE, Schisano M, Mauro LA, Sambataro G, Basile A, Vancheri C, Palmucci S. Chest imaging using signs, symbols, and naturalistic images: a practical guide for radiologists and non-radiologists. (2019) Insights into imaging. 10 (1): 114. doi:10.1186/s13244-019-0789-4 - Pubmed