What imaging finding is associated with reactivated tuberculosis?

The presence of upper lobe fibrocavitary lesions is a key imaging finding associated with reactivated tuberculosis. This presentation is typical because reactivated tuberculosis often occurs in individuals who have a previously contained infection, where the bacteria can become active again, particularly in areas of the lungs that have lower oxygen tension. The upper lobes are more susceptible due to their higher oxygen content, which favors the survival of the Mycobacterium tuberculosis organism.

These lesions appear as cavitary spaces on imaging, typically manifested on chest X-rays or CT scans. The cavitation occurs as a result of necrosis of the lung tissue surrounding the granulomas, indicating ongoing inflammation and active disease.

In contrast, fibrocavitary lesions in the lower lobe are more commonly associated with primary tuberculosis or chronic lung disease rather than reactivation. Solitary small nodules can be seen in other forms of pulmonary infections or benign conditions but are not characteristic of reactivated TB. Similarly, pleural effusions alone may occur in various pulmonary conditions but are not as definitive for reactivated tuberculosis as the presence of upper lobe cavitary lesions.