What is the classic finding on CT scan of the chest in patients with ABPA?

The classic finding on a CT scan of the chest in patients with Allergic Bronchopulmonary Aspergillosis (ABPA) is central bronchiectasis. This is characterized by a permanent dilation of the bronchi, which occurs as a result of recurrent infections and inflammation, often associated with the hypersensitivity reactions to the Aspergillus species.

In ABPA, bronchiectasis tends to have a central location, typically affecting the proximal airways and can be a consequence of chronic inflammation and mucus plugging. Consequently, the presence of central bronchiectasis is not just a diagnostic clue; it also reflects the underlying pathophysiological processes occurring in the lungs of patients with ABPA.

Other findings on imaging, such as ground glass opacities, may be observed in various other pulmonary conditions, but they are not specific to ABPA. Similarly, pleural effusions and cardiomegaly can be related to numerous different causes and are not characteristic features of ABPA. Thus, the identification of central bronchiectasis on a CT scan serves as a key indicator of this condition and aligns with the typical presentation seen in affected patients.