Silicosis

Silicosis is a type of pneumoconiosis caused by crystaline silica inhalation. The likelihood for developing the disease is related to cumulative exposure to silica dust during the woker career. Due to the omnipresence of silica, this is one of the most common pneumoconiosis, because of that usually the term “silicosis” is used inappropiately as “pneumoconiosis” synonim. Otherwise, there are pneumoconiosis caused by mixed dust with a principal mineral and crystaline silica, as for instance, pneumoconiosis of the coal workers or graphite, which clinical and radiological characteristics are similar to silicosis and, because of that, they share the term.

Histological lung dumages are characterized by several nodules of different sizes (betwen 1 and 10 mm), randomly distributed in both lungs, mainly in upper lobules, which is a mild case of the disease, called Chronic Simple Silicosis. There are also other types of silicosis characterized by diffuse lung fibrosis which might be confused with idiopathic pulmonary fibrosis.

Different clinical forms of silicosis have different evolution and prognosis. Chronic silicosis can be declared after more than 10-15 of exposure duration; simple forms do not cause symptoms, nor reduce the survival rate compared with the rest of the population. Complicated silicosis, however, causes cough, fatigue, lung function changes, can produce complications and reduces the life expectancy. Moreover there are premature forms, such as accelerated silicosis, which can be developed after 1 to 5 years of exposure and acute silicosis which appears 6 to 12 month later. Both situations are related to very high dust exposures.

In order to get a correct silicosis diagnosis it is necessary to have a good clinical and employement histories, physical examination, thorax Rx and pulmonary function tests, and the exclussion of the rest of diseases related to the radiological alteration. All these test should be evaluated by an expert pneumologist. Thorax Rx is the basis test for the diagnosis. The CT of the thorax just should be used in case of doubt. Sometimes it is necessary to improve the study and it could be necessary to carry out an histological examination of the lung, which is frecuently done with a transbronchial lung biopsy through a bronchoscopy.

Nowadays, there is no an specific treatment for silicosis and in very advanced stages it could be necessary a lung transplantation. The only effective measure is primary prevention, keeping dust levels under the limit values according to the law. When a worker is diagnosed with silicosis, first suggestion is the interruption of the silica exposure.