Case 8

History
57-year-old male with history of TB presents with chronic cough.

PA chest radiograph shows a large left upper lobe thin-
walled cavity.

Decubitus chest view shows a freely moveable, large,
thin-walled cavitary mass in the left upper lobe.

Diagnosis?

Diagnosis
TB cavity with mycetoma.

Findings
Residual cysts or cavities in the upper lobes can harbor intracavitary mycetomas, or fungus balls. In this case, the cavity is secondary to tuberculosis, but it may result from many different causes. They are almost invariably in the upper lobes. The mass of fungus is usually spherical and irregular. It is often surrounded by air and moves when the patient's position is changed as shown on the decubitus view.

Mycetoma are most commonly caused by Aspergillus Fumigatus, although other fungi may be responsible. These mycetoma grow in a noninvasive saprophytic manner. Potentially fatal hemoptysis is a feature of intracavitary mycetoma. Thickening of the walls of TB cavities has been described as an early radiographic finding of Aspergillus colonization preceding mycetoma formation. The differential diagnosis should include a fragment of tissue in a necrotic carcinoma, a mass of necrotic lung in an abscess, disintegrating hydatid cysts, or intracavitary blood clot.