Asbestos, ergot drugs and the pleura.

In this issue of the Journal, two groups of researchers with established experience in asbestos-induced respiratory disease, independently report on patients with prior occupational exposure to asbestos, who developed exuda-tive pleural effusion and/or pleural thickening, while being treated with bromocriptine for Parkinson's disease [1, 2]. Ultimately, the pleural changes were largely reversible following drug withdrawal. Both groups prudently stressed that, since no control group was included, the interaction of, and possible potentiation between asbestos and ergot drugs currently remains speculative [1, 3]. Despite the lack of definitive epidemiological evidence that bromocriptine and asbestos act synergistically to induce pleural thickening, fibrosis or effusion, the Editorial Board of the Journal decided to have these papers published, as a possible warning sign in occupational/iatrogenic respiratory disease. The following pleural lesions are associated with asbestos exposure: hyaline or calcified plaques of the pari-etal pleura; diffuse pleural thickening or fibrosis involving the visceral pleura; benign exudative or haemorrhagic effusions; and the malignant mesothelioma [4–7]. The typical radiographic manifestations of asbestos-induced pleural lesions are distinctive [5, 6], but the diagnosis of early mesothelioma in patients with pleural thickening may be difficult. Classically, folding and shrinking of the lung, and rounded atelectasis [8–12] are ascribed to fibro-sis of the visceral pleura. Benign asbestos pleural effusion may be followed by pleural thickening or fibrosis, but rarely by the development of pleural mesothelioma [13]. Ergot drugs such as methysergide, ergotamine, dihydro-ergotamine, bromocriptine, nicergoline, pergolide, and dop-ergine, collectively known as ergolines, are utilized to treat symptoms or syndromes such as cluster headache, migraine, Parkinson's disease, or the organic brain dys-function syndrome [14, 15]. When administered in the long term, ergolines can also induce distinctive pleuro-pulmonary changes in a few patients, including parietal [14, 15] or visceral [15] pleural thickening, pleural effu-sion [14–17], rounded atelectasis [14], and fibrosis of the lung adjacent to pleural lesions [15, 18, 19]. Of note, and in contrast to what is seen in asbestos-related diseases [5], pleural changes induced by ergolines rarely, if ever, calcify [14], possibly because they develop over shorter periods of time. A marked elevation of the erythrocyte sedimentation rate (ESR) is common in association with ergoline-induced pleural changes, occasionally with figures over 100 mm in one hour [14, 15]. The histological transcript of radiographic pleural thickening or plaques is pleural fibrosis, whether ergo-lines or asbestos are the cause [4, 14, 15]. Thus, these two terms may be used interchangeably in this text. …