A hard metal pneumoconiosis is usually classified as a type of fibrotic pneumoconiosis where the precipitating agent consists of a hard metal (not a heavy metal) such as.
- tungsten/tungsten carbide alloys
- or a mixture
A broader term used is hard metal lung disease (HMLD) which also takes into account the non-fibrotic stages/forms such as bronchitis/obliterative bronchitis caused by hard metal lung disease.
Clinical presentation can be similar to that of hypersensitivity pneumonitis, with some patients having episodes of work-related subacute disease and some patients evolving, more or less rapidly, to lung fibrosis 6.
Hard metals are widely used for industrial purposes which require extreme hardness and high-temperature resistances, such as for cutting tools, oil well drilling, and jet engine exhaust ports 2. Hard metal utilisation plants can contain enclosed chamber and with each application, large volumes of fine aerosols can be created 3.
Histopathological manifestations of hard-metal disease can range from bronchitis to subacute fibrosing alveolitis to interstitial fibrosis 8.
Some authors outlined a set of diagnostic criteria which includes 8:
- history of exposure to metal dust
- characteristic clinical features, including shortness of breath, cough, and dyspnea on exertion over a prolonged period
- radiologic findings of interstitial lung disease
- histologic findings of interstitial lung disease or a giant cell interstitial pneumonia pattern (a large number of giant cells filling airspaces), with thickening of the interstitium and alveolar walls by mononuclear cells
- histopathologic finding of metallic content in lung tissue
Plain chest radiographic features are non-specific. A chest radiograph may be normal or show a nodular, reticulonodular, or reticular pattern 7.
An exposure history of hard metal is essential in image interpretation. Described features are non-specific on their own and a dependent on the stage. These include 5:
- reticulation 5,7
- traction bronchiectasis 5,8-9
- large peripheral cystic spaces in a mid and upper lung distribution 5
- patchy lobular bilateral ground-glass opacities 7-9
- areas of consolidation 7-9
- centrilobular nodularity 7
- honeycombing 7 (occasionally)
- 1. Forrest ME, Skerker LB, Nemiroff MJ. Hard metal pneumoconiosis: another cause of diffuse interstitial fibrosis. Radiology. 1978;128 (3): 609-12. Radiology (abstract) - doi:10.1148/128.3.609 - Pubmed citation
- 2. Cugell DW. The hard metal diseases. Clin. Chest Med. 1992;13 (2): 269-79. Pubmed citation
- 3. Figueroa S, Gerstenhaber B, Welch L et-al. Hard metal interstitial pulmonary disease associated with a form of welding in a metal parts coating plant. Am. J. Ind. Med. 1992;21 (3): 363-73. Pubmed citation
- 4. Moreira MA, Cardoso Ada R, Silva DG et-al. Hard metal pneumoconiosis with spontaneous bilateral pneumothorax. J Bras Pneumol. 2010;36 (1): 148-51. Pubmed citation
- 5. Gotway MB, Golden JA, Warnock M et-al. Hard metal interstitial lung disease: high-resolution computed tomography appearance. J Thorac Imaging. 2002;17 (4): 314-8. Pubmed citation
- 6. Nemery B, Abraham JL. Hard metal lung disease: still hard to understand. Am. J. Respir. Crit. Care Med. 2007;176 (1): 2-3. Am. J. Respir. Crit. Care Med. (full text) - doi:10.1164/rccm.200704-527ED - Pubmed citation
- 7. Dunlop P, MüLler NL, Wilson J et-al. Hard metal lung disease: high resolution CT and histologic correlation of the initial findings and demonstration of interval improvement. J Thorac Imaging. 2006;20 (4): 301-4. Pubmed citation
- 8. Chong S, Lee KS, Chung MJ et-al. Pneumoconiosis: comparison of imaging and pathologic findings. Radiographics. 2006;26 (1): 59-77. Radiographics (full text) - doi:10.1148/rg.261055070 - Pubmed citation
- 9. Kim KI, Kim CW, Lee MK et-al. Imaging of occupational lung disease. Radiographics. 2001;21 (6): 1371-91. Radiographics (full text) - Pubmed citation
Interstitial lung disease
interstitial lung disease
- drug-induced interstitial lung disease
- hypersensitivity pneumonitis
idiopathic interstitial pneumonia (mnemonic)
- acute interstitial pneumonia (AIP)
- cryptogenic organising pneumonia (COP)
- desquamative interstitial pneumonia (DIP)
- idiopathic non-specific interstitial pneumonia (NSIP)
- idiopathic pleuroparenchymal fibroelastosis
- lymphoid interstitial pneumonia (LIP)
- respiratory bronchiolitis–associated interstitial lung disease (RB-ILD)
- usual interstitial pneumonia / idiopathic pulmonary fibrosis (UIP/IPF)