Radiographic findings: Chest radiographs between 1989 and 1995 showed an approximately 2 cm nodule in the superior segment of the left lower lobe. It changed slightly in size and occasionally showed cavitation with an air-fluid level. Image A from 1989 shows a well-defined, solid nodule. Image B from 1992 shows cavitation with a smooth, thin, superior wall. The post-CABG film in 1995 (not shown) demonstrated resolution of the cavity, and the nodule was again solid in appearance and little changed in size.

A. 1989B. 1992

In 1/96 at the time of onset of fever and hemoptysis, the chest radiograph (not shown) demonstrated a marked increase in size of the mass (6 x 5 x 4.5 cm). CT (image C) from 4 days later shows a mild decrease in size of the ill-defined mass, which had soft-tissue attenuation and central, linear and irregular air, consistent with mild cavitation. Over the next year the mass again waxed and waned in size but did not reach a size beyond 4 x 3.5 cm.

C. 1/96

A chest radiograph (image D) obtained just before surgery in 12/96 shows the mass, which is mildly lobular and relatively well-defined.

D. 12/96

Differential diagnosis: The differential diagnosis for cavitary pulmonary nodules is extensive [1-3]. Fungal infections such as coccidioidomycosis, histoplasmosis, blastomycosis, and cryptococcosis may present as cavitary nodules, as may tuberculous and atypical mycobacterial infections and nocardiosis. Gram-negative and anaerobic bacterial abcesses can appear as cavitary, mass-like densities. Septic embolic lesions typically cavitate but are usually multiple. Rare infections such as hydatid cyst and amebic abcess can cavitate.

Cavitation occurs in 2% to 10% of bronchogenic carcinomas [2]; the cavities often demonstrate a thick, irregular wall. Metastatic lung nodules may cavitate, especially squamous cell-type, but also adenocarcinoma, sarcoma, melanoma, and rarely osteosarcoma. Both Hodgkin and non-Hodgkin lymphoma of the lung sometimes show cavitation [4].

The necrobiotic (non-infectious, inflammatory) nodules of Wegener granulomatosis and rheumatoid disease may cavitate and usually have thick cavity walls; they are frequently multiple. Cystic bronchiectasis can appear as thin-walled, cavitary densities. Bronchogenic cysts and intrapulmonary sequestration may cavitate. Uncommonly, sarcoidosis, amyoidosis, and silicosis show cavitary masses. Laryngeal papillomatosis occasionally spreads to the trachea and bronchi and rarely presents with lung nodules that cavitate [5].

The course of the disease in this case is difficult to reconcile with many of the etiologies listed above. Although infections may be indolent, the persistence of this lesion for years with recurrent cavitation would be very unusual for most infections. Primary or metastatic malignancy is even less likely to give such a prolonged course. Intrapulmonary bronchogenic cysts persist over years and can cavitate and harbor recurrent infections. Focal bronchiectasis could also appear as a nodule (filled with mucus) that changes size and appears to cavitate. Rheumatoid nodules can be indolent, and 50% cavitate, but they are multiple in 3/4 of patients and usually occur in patients with established rheumatoid arthritis [6]. The nodules of Wegener granulomatosis may be solitary in up to 1/3 of patients, cavitate in up to 1/2 of cases, but usually resolve over a period of months, and if the nodules relapse, they usually recur in new locations [6]. Pulmonary papillomatosis is uncommonly seen in children and adolescents, and rare in adults with laryngeal papillomatosis. It may present with atelectasis or bronchiectases, and can present with indolent lung nodules that cavitate [5]. Carcinomatous transformation is rare.

References

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 RL. Chest and Cardiac Imaging: an Atlas of Differential Diagnosis. New York, Raven Press, 1993, pp 58-63.

3. Reed JC. Chest Radiology: Plain Film Patterns and Differential Diagnoses, 4th ed. St. Louis, Mosby-Year Book, 1997, pp 394-403.

4. Blank N. Chest Radiographic Analysis. New York, Churchill Livingstone, 1989, p 221.

5. Fraser RS, Pare JAP, Fraser RG, Pare PD: Synopsis of Diseases of the Chest, 2nd ed. Philadelphia, W.B. Saunders Company, 1994, pp 489-490.

6. Wilson AG. Immunologic diseases of the lungs. In P Armstrong, A Wilson, P Dee, D Hansell (eds): Imaging of Diseases of the Chest., 2nd ed. St. Louis, Mosby-Year Book, 1996, p 494-505.

Case 8--Clinical Summary

Table of Contents