Radiologic findings: A plain film shows bilateral, rounded opacities at the costophrenic angles, which at first glance, suggest pleural effusions.
The CT scan, however, shows subpleural, rounded, pulmonary parenchymal densities at the lung bases. The soft tissue window image (left) shows that these mass-like densities contain lower-attenuation foci suggesting cavitation or necrosis.
Differential diagnosis:Etiologies of multiple, cavitary, pulmonary mass-like densities are extensive [1-3] and include infections (fungal, tuberculous, and nontuberculous mycobacterial infections, nocardiosis, gram-negative and anaerobic bacterial abcesses, septic emboli, hydatid cyst, and amebic abcess), lymphoma, metastatic disease, Wegener granulomatosis, rheumatoid necrobiotic nodules, sarcoidosis, amyloidosis, and respiratory papillomatosis (see discussion of radiographic findings for Case 8). Peripheral location of densities is seen with pulmonary infarcts, fungal and tuberculous granulomas, metastatic disease, rheumatoid nodules, Pancoast tumors, lymphoma, and atelectasis .
1. Armstrong P. Basic patterns in lung disease. In P Armstrong, A Wilson, P Dee, D Hansell, (eds): Imaging of Diseases of the Chest, 2nd ed. St. Louis, Mosby-Year Book, 1996, pp 96-97.
2. Eisenberg R. Chest and Cardiac Imaging: an Atlas of Differential Diagnosis. New York, Raven Press Ltd, 1993, pp 58-63.
3. Reed J. Chest Radiology: Plain Film Patterns and Differential Diagnoses, 4th ed. St. Louis, Mosby-Year Book, 1997, pp 394-403.
4. Reed J. Chest Radiology: Plain Film Patterns and Differential Diagnoses, 4th ed. St. Louis, Mosby-Year Book, 1997, p 25.
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