Monad sign - Air surrounding an aspergilloma
Air crescent Sign - Appearance of cavitation that may be seen with invasive apergillosis
The former (monad's sign) develops in immunologically competent patients with structural lung disease. The radiographic appearance is that of a gravity-dependent mass (fungus ball) within a preexisting cavity.
While the latter (air crescent sign) in invasive aspergillosis typically occurs in immunocompromised patients.
Air crescent Sign - Appearance of cavitation that may be seen with invasive apergillosis
The former (monad's sign) develops in immunologically competent patients with structural lung disease. The radiographic appearance is that of a gravity-dependent mass (fungus ball) within a preexisting cavity.
While the latter (air crescent sign) in invasive aspergillosis typically occurs in immunocompromised patients.