Review Question - QID 100932

The patient's positive acid-fast sputum sample accompanied by a characteristic Ghon complex likely represent primary tuberculosis.

Mycobacterium tuberculosis is an acid-fast bacteria known to be the causative agent of tuberculosis. Transmission relies on inhalation of small-particle aerosols covered in the bacteria. Primary tuberculosis is characterized by a fibrocavitary disease of the middle or lower lobes of the lung with/without involvement of hilar/mediastinal nodes. Together, these findings are termed a Ghon complex when visible on chest radiograph.

Figure A shows a chest radiograph of a patient with a Ghon complex and calcified hilar lymph nodes. Figure B shows a Ghon complex in a gross specimen of lung. You can appreciated the calcifications within the complex.

Incorrect Answers:
Answer 2: While adenocarcinoma can also present as a round lesion on chest radiograph along with hilar/mediastinal lymphadenopathy, it would not have a acid-fast positive sputum stain.
Answer 3: Miliary tuberculosis is characterized by dissemination of tiny foci of tuberculosis among the various organs of the body. There is no evidence of that here.
Answer 4: Coccidioidomycosis lesions are commonly found in the upper lobes of the lung and are caused by a fungus, not acid-fast organisms.
Answer 5: Secondary tuberculosis is characterized by a tendency to re-activate in the oxygen-rich upper lobes of the lung. It does not usually present with a Ghon complex.