Air crescent sign (aspergilloma)


This patient is neutropaenic but has improving cell counts. The development of an air crescent sign in the setting of angioinvasive aspergillosis is a good prognostic sign, denoting separation of the infarcted core from host response / granulation tissue. 

This should not be confused with an aspergilloma which occurs in patients with normal immunity and represents colonization by aspergillus of a previously existing cavity (most commonly TB).