Pleural lesions and the ILO classification: the need for a revision.

The ILO system for radiographic classification of pneumoconioses is a very important epidemiological tool. Unfortunately, the classification is not precise for pleural lesions, which are especially important for evaluation of asbestos-related diseases. The classification cannot separate extrapleural fat from diffuse thickening of the pleura, nor large plaques from diffuse thickening. In this paper, a short review of the different lesions are given and a revised scheme is suggested. This scheme includes as separate lesions: pleural fat; lesions of the parietal pleura, i.e., pleural plaques; and lesions of the visceral pleura, i.e., diffuse thickening and rounded atelectasis. The extent and width, as in the present ILO scheme, could be abolished.