A 55-year-old man treated for pulmonary tuberculosis 15 years ago now presents with recurrent hemoptysis. CT shows a thin-walled cavity in the right apex containing a rounded mass with a crescent of air around its upper border. The mass changes position between supine and erect films. The most likely causative organism is:

• A Cryptococcus neoformans
• B Mycobacterium avium intracellulare
• C Histoplasma capsulatum
• D Aspergillus fumigatus ✓

Explanation

An aspergilloma (fungus ball) colonizes a pre-existing pulmonary cavity, classically from healed tuberculosis or sarcoidosis. It appears as a mobile round mass with an air crescent (Monod sign when the crescent precedes the ball), and hemoptysis is the typical presentation. MAC and Histoplasma can cause nodules or pneumonia in cavities but do not form mobile intracavitary balls, and cryptococcus causes pneumonia or meningitis predominantly in immunosuppressed hosts.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.