Although silicosis has been recognized for many centuries, its prevalence increased markedly with the introduction of mechanized mining. The prevalence has declined markedly in developed countries in recent decades because of effective industrial hygiene measures.
Simple silicosis manifests as multiple small (< 10 mm) nodules that are scattered diffusely throughout the lungs but may be more prominent in the upper lung fields. These radiographic findings have been found to correlate well with pathologic findings. Chest radiographic findings in persons with simple silicosis have a high degree of sensitivity and specificity. Calcification of the hilar lymph nodes, particularly in the rim of the nodes (ie, eggshell calcification) is very characteristic of silicosis. However, eggshell calcifications are observed only in a minority of cases of silicosis. Other causes of eggshell calcification include sarcoidosis, histoplasmosis, and irradiation. Rarely, the pulmonary nodules also may show calcification.
The diagnosis of silicosis is based on history of exposure, chest radiographic appearance consistent with silicosis, and an absence of other diagnoses that simulate the radiographic abnormalities of silicosis. Clinical manifestations, symptoms, and physical examination findings provide support to the diagnosis. Thus, examination of lung tissue is seldom warranted. (Medscape)