A 45-year-old woman with sarcoidosis has chest CT showing 'galaxy sign'. This refers to:
- A Bilateral hilar lymphadenopathy surrounding the pulmonary artery
- B A large nodule surrounded by satellite micronodules along lymphatics, resembling a galaxy ✓
- C Multiple ring-shaped opacities in the lung periphery
- D Ground-glass halo around a central calcified nodule
Correct answer: B. A large nodule surrounded by satellite micronodules along lymphatics, resembling a galaxy
Explanation
The galaxy sign in sarcoidosis describes a large rounded nodule (coalescent granulomas) surrounded by smaller satellite nodules radiating outward like stars in a galaxy. It is seen on CT and correlates with clusters of granulomas along bronchovascular bundles and lymphatics. This sign is characteristic of sarcoidosis and progressive massive fibrosis in pneumoconiosis. The halo sign (ground-glass around a nodule) is different and typically indicates angioinvasive aspergillosis.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.