[Pulmonary silicosis associated with MacLeod syndrome: a case report]

The paper reports a case of silicosis associated with idiopathic unilateral hyperlucent lung--MacLeod's disease (ML)--in a 65-year old miner. ML had not been diagnosed before this clinical observation and the patient had been exposed to silica dust for about 15 years as a truck operator in water supply tunnelling work in central Italy. Impaired ventilatory function due to left pulmonary dystrophy was the favouring or even the causal factor of dust accumulation in the functionally active right lung and of the tissue reaction to the dust, leading to interstitial fibrosis. A radiological diagnosis of p 1/0 pneumoconiosis was made according to the 1980 International Labour Office classification. Clinical, radiological and functional findings indicated the presence of respiratory failure as a result of the sum of silicotic and dystrophic lesions. Two combined pulmonary scintigraphic examinations with Tc99 perfusional and mTc-DPTA inhalatory methods revealed peculiar alterations: absence of ventilation associated with severe vascular impairment in the left lung, inequality of the ventilation/perfusion rate, due to pneumoconiosis, in the right lung. MacLeod's disease is rare, but must be considered as a mandatory contra-indication for work involving dust exposure risk since it is one of the predisposing factors which can cause an occupational disease even if environmental exposure standards are observed.