Air crescent sign

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Air crescent sign
Air crescent sign.jpg
The arrows denote an ill-defined nodular opacity in medial aspect of right upper lobe with ill-defined rim of lucency surrounding it
Differential diagnosis Aspergilloma

In radiology, the air crescent sign (also called the Monad sign [1] ) is a finding on chest radiograph and computed tomography that is crescenteric and radiolucent, due to a lung cavity that is filled with air and has a round radiopaque mass. [2] Classically, it is due to an aspergilloma, a form of aspergillosis, that occurs when the fungus Aspergillus grows in a cavity in the lung. [3]

Contents

Air cresent sign has also been reported in conditions such as tuberculosis, Wegener granulomatosis, intracavitary hemorrhage and lung cancer. [4]

Additional images

Sagittal reformat from a CT scan of the chest showing air crescent sign in a patient with invasive fungal infection. There is a rounded cavity in the apical right upper lobe, with a non-dependant soft-tissue nodule within it. Also there is some subtle ground-glass opacity surrounding the lesion. Invasive fungus.JPG
Sagittal reformat from a CT scan of the chest showing air crescent sign in a patient with invasive fungal infection. There is a rounded cavity in the apical right upper lobe, with a non-dependant soft-tissue nodule within it. Also there is some subtle ground-glass opacity surrounding the lesion.

References

  1. ↑ Goel, Ayush. "Pulmonary aspergillosis". Mediconotebook. Retrieved 29 May 2015.
  2. ↑ Abramson S (January 2001). "The air crescent sign" . Radiology. 218 (1): 230–2. doi:10.1148/radiology.218.1.r01ja19230. PMID   11152807.
  3. ↑ Curtis AM, Smith GJ, Ravin CE (October 1979). "Air crescent sign of invasive aspergillosis". Radiology. 133 (1): 17–21. doi:10.1148/133.1.17. PMID   472287.
  4. ↑ Hansell, David M.; Bankier, Alexander A.; MacMahon, Heber; McLoud, Theresa C.; Müller, Nestor L.; Remy, Jacques (March 2008). "Fleischner Society: Glossary of Terms for Thoracic Imaging". Radiology. 246 (3): 697–722. doi:10.1148/radiol.2462070712. ISSN   0033-8419 . Retrieved 3 January 2026.
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