Disease: Complicated Silicosis

Clinical Information:

This 69 year old male presented with dyspnea on exertion and shortness of breath. He was a hardrock miner with significant silica exposure for 22 years. He has had a slow decline in his lung function and exercise capabilities.

Imaging:

Simple silicosis is characterized by small round nodules, fairly uniform in size with an upper lung predominance. With progression of the disease, the nodules coalesce and form conglomerate masses as shown in this series of CXRs. The films also demonstrate mediastinal and hilar lymphadenopathy which is usually present. Eggshell calcification of lymph nodes occurs in 4-5% of workers.

The designation of complicated silicosis is used when conglomerate masses are greater than 1 cm. in diameter. The masses can reach 10 cm. in diameter and there is associated cicatrization atelectasis of the upper lobes, hilar retraction, bibasilar hyperexpansion and emphysema. The masses may undergo ischemic necrosis and cavitation. CT is useful in further characterizing the disease and can determine the presence of early coalescence and emphysema better than plain films. In this particular case, the CT clearly shows the calcified lymphadenopathy, the conglomerate masses and the surrounding emphysema.

Discussion:

Silicosis is a chronic nodular fibrosing disease of the lungs caused by a prolonged exposure to free crystaline silica. Almost all cases of silicosis are due to occupational exposure through hard rock mining, sandblasting, or foundry work. Silicosis is produced by the inhalation of silica particles and their cytotoxic effect on the lungs. A diagnosis of silicosis depends on a history of silica exposure and chest radiographic abnormalities. Simple silicosis occurs in 10-20% of exposed workers; complicated silicosis occurs in 1-2%.

Differential Diagnosis (DDx):

Coal Worker's Pneumoconiosis

Sarcoidosis

References:

Gamsu G. Computed Tomography and High Resolution Computed Tomography of Pneumoconioses. Journal of Occupational Medicine July 1991; 33: 794-796.

Stark P., Jacobson F., Shaffer K. Standard Imaging in Silicosis and Coal Worker's Pneumoconiosis. Radiologic Clinics of North America. 1992; 30: 1147-1154.

Case contributed by Debra Dyer, MD.


Debra Dyer, MD