P13 Clinical, radiographic and pulmonary function findings in silicosis

Introduction Silicosis is a pneumoconiosis caused by the inhalation of respirable silica. The condition is irreversible, and may be complicated by other pulmonary and non-pulmonary diseases. We describe clinical, radiographic and pulmonary function testing characteristics in a case series of silicosis. Methods Cases were identified from clinics in two Edinburgh teaching hospitals. The diagnosis was based on characteristic radiographic features and a history of exposure to respirable silica; in two subjects silicosis was confirmed by surgical biopsy. Average length of follow up was 64 months. Results 18 cases were identified, all were male. Median age = 52 years (range 28–66). 12 subjects worked as stonemasons, 5 as miners and 1 in a brick works. Common symptoms at presentation were dyspnoea (61%), cough (44%) and sputum (33%) but one-third were entirely asymptomatic and identified by radiological screening. Asymptomatic subjects tended to be younger; median 41 (range 28–66) vs 53 (range 28–66). 15 subjects (83%) had an abnormal CXR; the remainder had abnormalities on HRCT only. PMF was present in 9 cases (50%), one of whom was asymptomatic, and significant emphysema was present in 2 cases (11%). 60% of subjects with simple silicosis had normal spirometry and normal transfer factor (TCO). Seven subjects had obstructive spirometry; four were ex- or current smokers (average 16.5 pack years) and three never smokers. Only three subjects had a restrictive defect on spirometry, two of whom had radiographic evidence of PMF. 81% with a reduction in gas transfer had either a smoking habit or PMF. Lymphopenia was present in six subjects. Ten subjects had immunology performed; four were positive for anti-nuclear antibodies; one subject had a pre-existing diagnosis of systemic sclerosis and one subsequently developed SLE. All subjects had normal renal function. Two subjects developed mycobacterium tuberculosis and two (both smokers) developed bronchogenic carcinoma. Conclusions Despite the risks of silicosis being well described and legislation aimed at controlling silica exposure local experience suggests a resurgence of silicosis, particularly amongst younger workers who may be asymptomatic and may not have significant lung function changes.