Occupational Medicine Advance Access published July 1, 2015 Occupational Medicine doi:10.1093/occmed/kqv092
CASE REPORT
Hypersensitivity pneumonitis in a high school teacher A. Moniodis, T. Hamilton, E. Racila, B. Cockrill and R. McCunney Brigham and Women’s Hospital, Division of Pulmonary and Critical Care Medicine, PBB-CA-3, 75 Francis Street, Boston, MA 02115, USA. Correspondence to: A. Moniodis, Brigham and Women’s Hospital, Division of Pulmonary and Critical Care Medicine, PBB-CA-3, 75 Francis Street, Boston, MA 02115, USA. Tel: +1 734 239 3392; e-mail:
[email protected] Hypersensitivity pneumonitis (HP) is an inflammatory lung disease mediated by an immunological response to an inhaled antigen. Outbreaks of HP have been reported in industrial settings where manufacturing workers are exposed to water-based metalworking fluids (MWFs). Water-based MWFs promote growth of microorganisms and can be easily aerosolized and are thus potential aetiological agents of HP. We present a case of HP caused by exposure to water-based MWF in a vocational high school teacher. Culture of MWF used at his school grew Pseudomonas pseudoalcaligenes. This is the first known report of MWF-induced HP outside an industrial setting. The growth of Pseudomonas spp in this case recalls the earliest reports of the microbiology of MWF-induced HP and suggests that routine bacterial culture may be useful in the diagnosis of HP in workplaces without standard cleaning and biocide regulations.
Key words
Hypersensitivity pneumonitis; lung disease; occupational hygiene.
Introduction Hypersensitivity pneumonitis (HP), an inflammatory lung disease mediated by an immunological response to inhaled antigen, can be challenging to diagnose [1]. Symptoms overlap with other interstitial lung diseases, antigen exposure can be difficult to identify and laboratory and radiographic findings are non-specific. A history of exposure to a potential aetiological agent and typical symptoms along with supportive imaging and immunological studies are customarily used to make a diagnosis [2]. HP induced by exposure to metalworking fluids (MWFs) was first recognized in 1983 [3]. MWFs are widely used in metal manufacturing as coolants and lubricants and originally were oil-based. In the 1980s, formulations became water-based due to environmental regulations and were subsequently linked to HP outbreaks in industrial workers. These outbreaks were tied to growth of bacteria, mycobacteria and fungi in the waterbased MWFs and it is now known that aerosolization of the contaminated MWFs and resulting inhalation of organic antigens causes HP in susceptible individuals [3]. To date HP linked to MWFs has been described exclusively in industrial settings, usually as outbreaks at manufacturing sites [4]. Isolated cases probably occur
but remain unrecognized due to difficulties in diagnosing HP. We present a case of MWF-induced HP in a high school vocational classroom teacher.
Case report A 45-year-old man presented with a 1 year history of cough, shortness of breath and fatigue. His past medical history included tetralogy of Fallot with complete repair. The patient, a lifelong non-smoker, worked at a vocational school, teaching in the machine shop. He set up machines that used water-based MWFs and used them for 6 h daily for 5 days each week. He reported mild improvement of his symptoms over the summer holiday. No other teachers or students had similar symptoms. He had no pets. His home was newly constructed with no episodes of water damage and without hot tubs or mould. On physical examination, his lungs were clear to auscultation. Cardiac examination revealed a 2/6 systolic murmur in the midline. Physical examination was otherwise normal. A differential blood count showed 11 600 leukocytes/ mm3. Computed tomography (CT) showed multiple small patchy nodular opacities throughout the right lung, bronchocentric in distribution, with mild similar changes
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Abstract
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Figure 1. CT image, axial view: bronchocentric distribution of nodular opacities in the right lung with minimal similar change on the left.
A
Consequently, the machine coolant was >1 year old. Air sampling noted levels of coolant below the detectable limit of the sampling method, but operators were exposed to coolant mist while machine covers were open for set-up and maintenance. The industrial hygiene report recommended replacing the coolant with a fungicide/bactericide formulation and instituting a timeline for fluid change-out procedures and machine cleaning. Personal hygiene equipment and student education were also recommended.
Discussion HP to MWFs has been exclusively reported in manufacturing, primarily in the automotive and aeronautic industries [3]. We present the first case of HP to MWFs outside an industrial setting in a community vocational high school. As is customary in occupational medicine [5], the diagnosis of HP is a sentinel event that identifies a source of exposure and potential for improved workplace hygiene. Our identification of HP in a high school suggests that attention should be paid to MWF practices outside industrial settings, including schools with potential teacher and student exposure. Furthermore, the finding of MWF-induced HP unrelated to an industrial outbreak should prompt physicians to have a higher index of suspicion for those exposed to any water-based processes. The MWF from our patient’s workplace grew P. pseudoalcaligenes, in contrast to recent outbreaks in which Mycobacterium immogenum has been the most common microbiological agent identified [6]. However, the MWF culture in our case is consistent with the microbiology reported in the first cases of MWF HP, with Pseudomonas fluorescens cultured from the exposure fluid of car industry workers [7]. Pseudomonas species have also been cultured from MWFs in industrial settings without standard cleaning and biocide regimens [8], and the ubiquity of Pseudomonas species has been attributed to the aqueous nature of MWFs that provide a suitable medium [9]. MWFs treated with biocides eliminate this niche for Pseudomonas, leading to a selection of resistant organisms
B
Figure 2. Lung biopsy: on low-power view (Panel A) a peribronchiolar granuloma is observed (closed arrow), associated with non-specific chronic interstitial inflammation and small foci of organizing pneumonia (open arrows). The inflammatory infiltrate is mixed and comprised of lymphocytes, plasma cells and scattered eosinophils. Some granulomas (Panel B) have multinucleated giant cells (closed arrow) and the inflammatory infiltrate also contains occasional eosinophils (open arrow) (haematoxylin and eosin ×20 magnification, ×40 magnification).
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on the left (Figure 1). Pulmonary function testing (PFT) showed normal spirometry and lung volumes, but an impaired diffusion capacity (DLCO, 57% predicted). Bronchoalveolar lavage revealed 58% lymphocytes and 3% eosinophils and cultures for bacteria, fungi and mycobacteria were negative. Video-assisted thoracoscopic biopsies showed airway-centred lymphocytic infiltrate with patchy interstitial and airspace-containing poorly formed granulomas (Figure 2), consistent with HP. A serum hypersensitivity panel was negative. A culture of the school’s MWFs showed profuse growth of Pseudomonas pseudoalcaligenes. The patient stopped work, was treated with prednisone 60 mg daily and his symptoms improved. He completed a taper of prednisone and returned to work. His symptoms did not recur. Follow-up PFT showed improvement in DLCO to 76% predicted. An industrial hygiene assessment revealed four computer numerical control machines in the machine shop that used water-based spray coolant. Each machine had enclosures without exhaust ventilation to control coolant mist. The maintenance change-out procedure for the machines did not include changing the fluids regularly.
A. MONIODIS ET AL.: HYPERSENSITIVITY PNEUMONITIS IN A TEACHER Page 3 of 3
Key points
•• This report describes the first case of hypersensi-
tivity pneumonitis to metalworking fluids outside an industrial setting and diagnosed in a high school teacher in a community vocational classroom. •• We recommend both the consideration of the diagnosis of metalworking fluid-induced hypersensitivity pneumonitis for patients exposed to any water-based processes as well as evaluation of metalworking fluid hygiene practices in sites not currently regulated by industry standards. •• Metalworking fluid from the classroom grew Pseudomonas pseudoalcaligenes, consistent with the earliest reports of metalworking fluid-induced hypersensitivity pneumonitis, and suggests a role for routine bacterial culture in the evaluation of hypersensitivity pneumonitis in workplaces without standard cleaning and biocide regulations.
Conflicts of interest None declared.
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such as mycobacteria [8]. Mycobacterium can be difficult to culture from MWFs, whereas, as in our case, Pseudomonas is cultured with routine methods. An atypical aspect of our case is the finding on CT. Although no one radiographic pattern is pathognomonic for HP, characteristic findings are bilateral and diffuse, with upper and middle lobe predominance [10]. Our patient’s abnormalities were asymmetric and without upper lobe predominance. As HP requires an immune response delivered haematogenously, one theory is that our patient’s asymmetric findings are due to differences in pulmonary blood flow that resulted from his tetralogy of Fallot repair. Alternatively, this finding suggests a spectrum of radiographic findings associated with HP, including unilateral presentation, not previously recognized. In summary, HP occurred in response to water-based MWFs growing Pseudomonas species in a high school machine shop teacher. This diagnosis emphasizes the need for clinical suspicion in diagnosing HP in patients with a history of exposure to water-based aerosols. Routine bacterial culture of MWF fluid may help in making the diagnosis.
