Which radiographic finding is most characteristic of tuberculosis?

• A. Pleural effusion
• B. Diffuse interstitial infiltrates
• C. Apical pulmonary infiltrates
• D. Lobar consolidation

Answer: (C)

TB reactivation tends to involve the upper parts of the lungs because oxygen tension is higher there, which favors Mycobacterium tuberculosis growth. On chest radiographs this most often appears as an infiltrate in the apical (upper) lung zones, and often progresses to cavitation in advanced disease. This apical, cavitary pattern is much more characteristic of TB than the other patterns listed. Pleural effusion can occur with TB but isn’t as distinctive; diffuse interstitial or miliary patterns can occur with disseminated disease; and lobar consolidation is more typical of bacterial pneumonia. So the apical pulmonary infiltrates best reflect TB on imaging.