Extrinsic Allergic
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Chest clinic Thorax: first published as 10.1136/thoraxjnl-2014-205251 on 8 July 2014. Downloaded from CASE BASED DISCUSSION Lesson of the month: extrinsic allergic (bronchiolo) alveolitis and metal working fluids Paul Cullinan,1 Eva D’Souza,2 Rachel Tennant,3 Chris Barber4 1Department of Occupational INTRODUCTION since he had never kept them, a probable attribu- and Environmental Medicine, One of us was asked to consider a diagnosis of tion to ‘birds’ had been made. He had been Imperial College (NHLI) and Royal Brompton Hospital, occupational asthma for a man who had worked treated, intermittently, with high doses of prednis- London, UK for 20 years as a metal turner in a large, modern olone with no evidence of lasting benefit. The 2Health Management Limited, factory producing specialised machine parts. He survey of other employees and subsequent specialist London, UK 3 described a 2 year history of severe breathlessness investigation established a further two cases of Department of Respiratory that improved when he was not at work. His spir- occupational bronchioloalveolitis with probable Medicine, Northwick Park – Hospital, London, UK ometry was restrictive with a FEV1 of 1.35 L (40% onset in 2010 2011. 4Centre for Workplace Health, predicted) and FVC of 1.8 L (45% predicted), a Northern General Hospital, ratio of 75%. Other lung function measurements DISCUSSION Brearley Outpatient, Herries indicated gas trapping; his TLC was 5.01 L (79% These five men had a diagnosis and an occupation in Road, Sheffield, UK predicted) and RV/TLC 170% predicted. A high common; all were metal machinists in a single Correspondence to resolution CT scan of his lungs revealed a wide- factory, a job that entails exposure to mists of metal Dr Paul Cullinan, Department spread ‘mosaic’ pattern of attenuation indicative of working fluids (MWFs). Inhalation of MWF is well of Occupational and small airflow obstruction. We made a diagnosis of recognised as a cause of extrinsic allergic bronchio- Environmental Medicine, occupational extrinsic allergic bronchioloalveolitis loalveolitis (in this context a more accurate term than Imperial College (NHLI) and 12 Royal Brompton Hospital, and recommended that he change his work. After hypersensitivity pneumonitis), but it appears, from 1b Manresa Road, 12 months working elsewhere in the same this experience, that the association is not widely London SW3 6LR, UK; company, away from the machine shop, his dys- appreciated by respiratory physicians. p.cullinan@imperial.ac.uk pnoea was greatly improved but had not disap- Machining or ‘turning’ metal parts on a lathe is a Received 4 June 2014 peared; his FVC had increased to 2.41 L, his FEV1 skilled occupation used in the manufacture of a Revised 24 June 2014 to 1.45 L and his TLC to 5.36 L. very wide variety of components; this is often done Accepted 25 June 2014 Four months later we were referred a man who using cutting tools controlled by a computer and http://thorax.bmj.com/ Published Online First was also a metal turner in the same factory. For metalworking machinists in the UK and elsewhere Chest clinic 8 July 2014 2 years he had been a patient in a specialist intersti- may describe themselves as ‘computer numerical tial lung disease clinic with a diagnosis of chronic control’ operators. Other terms include computer hypersensitivity pneumonitis. A marked lymphocy- numerical control grinder, turner, tool setter, cutter tosis in his bronchoalveolar lavage suggested and machinist. Metal shaping and grinding com- ongoing exposure to an external cause. The nature monly involves the use of MWF (in the UK also of this had not been established although the posi- known as ‘coolant’, ‘cutting fluid’ or ‘suds’)to tive findings of an autoimmune screen had led to lubricate the process, to control its temperature and conjecture of an ‘autoimmune’ aetiology, and of a to carry away the waste metal (‘swarf’). The on September 30, 2021 by guest. Protected copyright. high level of serum-specific IgG antibodies to machines are generally enclosed and may be Aspergillus species, that exposure to ‘mould at exhaust-ventilated to reduce—but rarely eliminate home or work’ might be relevant; an occupational —the escape of MWF mist into the atmosphere. history noted only that he worked for a machine MWF is collected and recirculated, often with parts manufacturer. While continuing to work he several machines sharing a common ‘sump’ or res- had been treated with pulsed methylprednisolone, ervoir. Systems of MWF management are required cyclophosphamide, prednisolone, mycophenolate to replenish and maintain its effectiveness and to and N-acetyl cysteine with little evidence of monitor levels of microbial contamination. In the success. His referral was occasioned by a (new) factory above, new lathes had been installed in physician noting that his symptoms improved when 2010; in contrast with those they replaced, the new Open Access he was not at work. On being informed that his machines were capable of being operated continu- Scan to access more free content illness was in all probability caused by his occupa- ously for 24 h and used a far higher volume of tion, he chose not to return to work. Six months MWF. These changes probably led to far higher later, without any specific treatment, his lung func- concentrations of MWF mist in the air of the shop tion measurements had started to improve. floor. Following the first diagnosis, discussion with the Most modern MWFs are complex emulsions of factory’s occupational health service led to a sys- water and a mineral, synthetic or semisynthetic oil; tematic survey of 250 employees who worked in they also contain a wide range of chemical additives To cite: Cullinan P, the same area. Through this we established that designed to enhance their performance and limit D’Souza E, Tennant R, et al. another metal turner was a patient at a third hos- microbial growth. Allergic respiratory conditions Thorax 2014;69: pital with a diagnosis of hypersensitivity pneumon- due to water-containing MWFs date back to the – 1059 1060. itis made 2 years previously; to his bemusement, late 1980s, with challenge studies confirming cases Cullinan P, et al. Thorax 2014;69:1059–1060. doi:10.1136/thoraxjnl-2014-205251 1059 Chest clinic Thorax: first published as 10.1136/thoraxjnl-2014-205251 on 8 July 2014. Downloaded from of occupational asthma caused by chemicals such as ethanola- workforce to identify other affected workers. Investigating large mine and pine oil deodorants.2 More recently, a number of outbreaks is logistically challenging, and where possible should large outbreaks of respiratory disease have been reported in US involve a multidisciplinary team including occupational lung and European MWF-exposed workers, with cases of extrinsic disease specialists, occupational health providers and occupa- allergic (bronchiolo)alveolitis (EAA), occupational asthma, bron- tional hygienists.5 In the outbreak above, careful scrutiny of all chitis and humidifier fever.2 Although difficult to prove, the exposed employees indicated that the problem was confined to aetiology of the outbreaks is thought to be due to poor control a small area of the shop floor; following extensive remedial of MWF mists, linked with microbial contamination occurring works to control MWF mists there have been no further cases. during their recirculation and prolonged use. Evidence to Over the last decade, MWF exposure has become the most support this comes from the unpredictable nature of the out- commonly reported cause of occupational EAA in the UK, breaks and the demonstration of IgG antibodies to a range of responsible for approximately half of all cases. We recommend bacteria, fungi and environmental mycobacteria in the serum of that all patients with suspected EAA (and other patterns of inter- exposed workers (with and without disease).3 stitial lung disease) are routinely asked about MWF exposures, A high index of suspicion is required in EAA due to MWF and that all potential cases are discussed as soon as possible with exposure as the symptoms are often non-specific and may be pro- an occupational lung disease centre. gressive, rather than clearly work-related. In some cases the pre- senting symptoms have been predominantly constitutional, with Correction notice This article has been corrected since it was Published Online First. The author Chris Barber’saffiliation has been amended. general malaise and unexplained weight loss. Long delays in fi reaching the correct diagnosis are not uncommon because symp- Contributors PC and RT identi ed the cases and wrote the manuscript with the assistance of ED and CB. toms are often attributed to asthma, COPD or to recurrent chest infections; or, as here, the diagnosis has been otherwise Competing interests None. explained. A HRCT with inspiratory and expiratory views in a Provenance and peer review Not commissioned; internally peer reviewed. period when the patient is symptomatic is probably the most Open Access This is an Open Access article distributed in accordance with the useful diagnostic tool. This may show typical features of bronch- Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which ioloalveolitis, with one or more of ground glass opacities, small permits others to distribute, remix, adapt, build upon this work non-commercially, 4 and license their derivative works on different terms, provided the original work is centrilobular nodules and lobular areas of gas trapping although properly cited and the use is non-commercial. See: http://creativecommons.org/ this last finding is not specific. In other cases however, the HRCT licenses/by-nc/4.0/ may appear normal (particularly during periods of relatively low exposure), or show a pattern of disease more suggestive of non- REFERENCES specific or usual interstitial pneumonitis. As with any other cause 1 Rosenman KD. Asthma, hypersensitivity pneumonitis and other respiratory diseases of EAA, early recognition and the prevention of further expo- caused by metalworking fluids.