Air crescent sign
Acute myeloblastic leukemia
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A rounded cavity in the apical right upper lobe, with a non-dependent soft-tissue nodule within it is noted. There is some subtle ground-glass opacity surrounding the lesion. There were several other similar lesions in the right lung (not shown).
- Note: This case has been tagged as "legacy" as it no longer meets image preparation and/or other case publication guidelines.
The imaging features, combined with the clinical history, are characteristic of invasive fungal infection, most commonly due to Aspergillus spp. Care should be taken to avoid confusion with mycetoma, which occurs in patients with pre-existing lung cavities, is gravity-dependent, and lacks the ground-glass halo.
Invasive aspergillosis occurs in immunosuppressed individuals and carries a 65-90% mortality rate if improperly treated. Cavitation occurs in the recovery phase and thus tends to indicate a better prognosis.
- Abramson S. The Air-Crescent Sign. Radiology. 2001; 218:230-232