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The Human Phenotype Ontology (HPO) is downloaded weekly from The file downloaded is considered the "last stable build" available for the ontology. For more about the HPO, view their website at

Term:Air crescent
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Accession:HP:0033661 term browser browse the term
Definition:An air crescent is a collection of air in a crescentic shape that separates the wall of a cavity from an inner mass. The air crescent sign is often considered characteristic of either Aspergillus colonization of preexisting cavities or retraction of infarcted lung in angioinvasive aspergillosis. However, the air crescent sign has also been reported in other conditions, including tuberculosis, Wegener granulomatosis, intracavitary hemorrhage, and lung cancer.
Comment:See Figure 3 of Hansell DM, et al., Fleischner Society: glossary of terms for thoracic imaging. Radiology. 2008;246:697-722.

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  Human phenotype 0
    Phenotypic abnormality 0
      Abnormality of the respiratory system 0
        Abnormal respiratory system morphology 0
          Abnormal pulmonary thoracic imaging finding 0
            Air crescent 0
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