Disease: Complicated Silicosis
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.
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.
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
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