E1801. Spectrum of Pulmonary Diseases From Aspergillus
  1. Rebecca Zhang; Hospital of the University of Pennsylvania
Aspergillus is a soil fungus that can cause 5 discrete categories of pulmonary diseases. Each category has distinct imaging and clinical features, and recognition of features of each group can help aid in prompt diagnosis and treatment. Aspergillus is commonly found in soil and on plants, including peanuts and corn. Most patients with normal immune systems can remove and clear the inhaled spores. However, immunocompromised patients or patients with chronic lung disease have risk factors that make infection much more likely.

Educational Goals / Teaching Points
Recognize common imaging features of the 5 main pulmonary aspergillus diseases (allergic bronchopulmonary aspergillosis, aspergilloma, semi-invasive, airway invasive, and angio-invasive). Describe risk factors, etiology, clinical presentation, and management of pulmonary aspergillosis diseases.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Allergic bronchopulmonary aspergillosis (ABPA) is a type I hypersensitivity leading to bronchiectasis. The finger in glove sign describes mucoid impaction within bronchiectasis and is not specific to ABPA. Aspergilloma is a gravity-dependent, mobile mass that changes position as the patient changes position. Radiography demonstrates a rounded mass within the cavity. CT demonstrates a cavity containing a fungus ball with consolidation surrounding the cavity. The "Monod sign" describes air surrounding the mycetoma in the cavity. Semi-invasive aspergillosis is necrotizing granulomatous inflammation from chronic aspergillus. CT shows segmental areas of consolidation that progresses slowly over months to years. Airway invasive aspergillosis is deep infection of the airway cells in immunocompromised patients. CT shows centrilobular and tree-in-bud nodules. Angioinvasive aspergillosis: Invasion and occlusion of small pulmonary arteries by the fungus in neutropenic patients. CT shows the halo sign, which describes a circular shadow of groundglass attenuation (corresponding to hemorrhage) around a consolidation. The air crescent sign describes a crescent of air surrounding the consolidation from retraction of the damaged lung and usually corresponds to recovery.

Pulmonary disease from aspergillus varies in risk factors, pathophysiology, clinical features, imaging features, and management. Recognition of classic imaging features from each category are crucial to help aid in prompt diagnosis of each distinct category of disease.