A 40-year-old man treated for angioinvasive aspergillosis during a period of neutropenia now has a recovering absolute neutrophil count. Repeat CT shows an air crescent between a rounded intracavitary mass and the cavity wall in the previously affected segment. This finding indicates:
- A Retraction of infarcted lung as neutrophil recovery begins ✓
- B Development of bronchopleural fistula
- C Progression to disseminated infection
- D Transformation into a bronchogenic carcinoma
Correct answer: A. Retraction of infarcted lung as neutrophil recovery begins
Explanation
The air crescent sign appears when marrow recovery allows neutrophils to reach the infarcted lung. Resorption and retraction of the necrotic sequestrum away from the cavity wall creates the crescent of air. It signals recovery rather than deterioration. C key distractor killer: the Monod sign looks identical but occurs in an aspergilloma within a pre-existing cavity such as old tuberculosis, whereas here the cavity formed de novo during invasive disease.
Reference: Grainger and Allison's Diagnostic Radiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.