Pathologic spectrum and lung dust burden in giant cell interstitial pneumonia (hard metal disease/cobalt pneumonitis): review of 100 cases

Pathology and Mineralogy of the Pneumoconioses

Pneumoconioses represent the spectrum of lung diseases caused by inhalation of respirable particulate matter small enough (typically <5-µm diameter) to reach the terminal airways and alveoli. Pneumoconioses primarily occur in occupational settings where workers perform demanding and skilled manual labor including mining, construction, stone fabrication, farming, plumbing, electronics manufacturing, shipyards, and more. Most pneumoconioses develop after decades of exposure, though shorter latencies can occur from more intense particulate matter exposures. In this review, we summarize the industrial exposures, pathologic findings, and mineralogic features of various well-characterized pneumoconioses including silicosis, silicatosis, mixed-dust pneumoconiosis, coal workers' pneumoconiosis, asbestosis, chronic beryllium disease, aluminosis, hard metal pneumoconiosis, and some less severe pneumoconioses. We also review a general framework for the diagnostic work-up of pneumoconioses for pulmonologists including obtaining a detailed occupational and environmental exposure history. Many pneumoconioses are irreversible and develop due to excessive cumulative respirable dust inhalation. Accurate diagnosis permits interventions to minimize ongoing fibrogenic dust exposure. A consistent occupational exposure history coupled with typical chest imaging findings is usually sufficient to make a clinical diagnosis without the need for tissue sampling. Lung biopsy may be required when exposure history, imaging, and testing are inconsistent, there are unusual or new exposures, or there is a need to obtain tissue for another indication such as suspected malignancy. Close collaboration and information-sharing with the pathologist prior to biopsy is of great importance for diagnosis, as many occupational lung diseases are missed due to insufficient communication. The pathologist has a broad range of analytic techniques including bright-field microscopy, polarized light microscopy, and special histologic stains that may confirm the diagnosis. Advanced techniques for particle characterization such as scanning electron microscopy/energy dispersive spectroscopy may be available in some centers.

Tungsten toxicity and carcinogenesis

Tungsten is an emerging contaminant in the environment. Research has demonstrated that humans are exposed to high levels of tungsten in certain settings, primarily due to increased use of tungsten in industrial applications. However, our understanding of the potential human health risks of tungsten exposure is still limited. An important point we have learned about the toxicity profile of tungsten is that it is complex because tungsten can often augment the effects of other co-exposures or co-stressors, which could result in greater toxicity or more severe disease. This has shaped the tungsten toxicology field and the types of research questions being investigated. This has particularly been true when evaluating the toxicity profile of tungsten metal alloys in combination with cobalt. In this chapter, the current state of the tungsten toxicology field will be discussed focusing on data investigating tungsten carcinogenicity and other major toxicities including pulmonary, cardiometabolic, bone, and immune endpoints, either alone or in combination with other metals. Environmental and human monitoring data will also be discussed to highlight human populations most at risk of exposure to high concentrations of tungsten, the forms of tungsten present in each setting, and exposure levels in each population.

Giant Cell Interstitial Pneumonia In Native, Transplanted And Re-Transplanted Lungs 8 Years Apart Without Known Hard Metal Exposure

Pneumoconioses are a group of non-neoplastic pulmonary disorders caused by inhaled inorganic particles. Well-described pneumoconioses include asbestosis, silicosis, coal worker's pneumoconiosis, chronic beryllium disease, and hard metal lung disease. Giant cell interstitial pneumonia (GIP) is a distinctive and rare pneumoconiosis most frequently found in workers exposed to hard metals, primarily cobalt and tungsten carbide. The pathologic picture is considered virtually pathognomonic for hard metal lung disease, although this dogma has been questioned by a few reports of giant cell interstitial pneumonia in patients without apparent hard metal exposure. Giant cell interstitial pneumonia is even rarer in lung transplant recipients. Here, we present a patient without known hard metal exposure who was found to have persistent giant cell interstitial pneumonia in native, transplanted and re-transplanted lungs 8 years apart.

PTX3 alleviates hard metal-induced acute lung injury through potentiating efferocytosis

Prolonged exposure to hard metal dust results in hard metal lung disease (HMLD) characterized by respiratory symptoms. Understanding the pathogenesis and pathological process of HMLD would be helpful for its early diagnosis and treatment. In this study, we established a mouse model of hard metal-induced acute lung injury through one-time intratracheal instillation of WC-Co dust suspension. We found that WC-Co treatment damaged the lungs of mice, leading to increased production of IL-1β, TNF-α, IL-6 and IL-18, inflammatory cells infiltration and apoptosis. In vitro, WC-Co induced cytotoxicity, inflammatory response and apoptosis in macrophages (PMA-treated THP-1) and epithelial cells (A549) in a dose-dependent manner. Moreover, RNA-sequence and validation experiments verified that Pentraxin 3 (PTX3), an important mediator in the regulation of inflammation, was elevated both in vivo and in vitro induced by WC-Co. Functional experiments confirmed the PTX3, which was located on the membrane of apoptotic cells, promoted macrophage efferocytosis efficiently. This progress could help block the lung inflammation and contribute to the rapid recovery of WC-Co-induced acute lung injury. These observations provide a further understanding of the molecular mechanism of WC-Co-induced pulmonary injury and disclose PTX3 as a new potential therapeutic approach to relieve WC-Co-induced acute lung injury via efferocytosis.

Inhalation of tungsten metal particulates alters the lung and bone microenvironments following acute exposure

Inhalation of tungsten particulates is a relevant route of exposure in occupational and military settings. Exposure to tungsten alloys is associated with increased incidence of lung pathologies, including interstitial lung disease and cancer. We have demonstrated, oral exposure to soluble tungsten enhances breast cancer metastasis to the lungs through changes in the surrounding microenvironment. However, more research is required to investigate if changes in the lung microenvironment, following tungsten particulate exposure, can drive tumorigenesis or metastasis to the lung niche. This study examined if inhalation to environmentally relevant concentrations of tungsten particulates caused acute damage to the microenvironment in the lungs and/or systemically using a whole-body inhalation system. Twenty-four female BALB/c mice were exposed to Filtered Air, 0.60 mg/m3, or 1.7 mg/m3 tungsten particulates (< 1 µm) for 4 h. Tissue samples were collected at day 1 and 7 post-exposure. Tungsten accumulation in the lungs persisted up to 7 days post-exposure and produced acute changes to the lung microenvironment including increased macrophage and neutrophil infiltration, increased levels of pro-inflammatory cytokines IL-1β and CXCL1, and an increased percentage of activated fibroblasts (α-SMA+). Exposure to tungsten also resulted in systemic effects on the bone, including tungsten deposition and transient increases in gene expression of pro-inflammatory cytokines. Taken together, acute whole-body inhalation of tungsten particulates, at levels commonly observed in occupational and military settings, resulted in changes to the lung and bone microenvironments that may promote tumorigenesis or metastasis and be important molecular drivers of other tungsten-associated lung pathologies such as interstitial lung disease.

Cobalt-related interstitial lung disease or hard metal lung disease: A case series of Chinese workers

Hard metal lung disease (HMLD) is rarely diagnosed and is caused by the occupational inhalation of hard metal dust, mainly cobalt. The diagnosis of HMLD is based on a thorough occupational dust exposure combined with clinical-radiological-histological findings. We present a series of four Chinese workers who had occupational exposure to cobalt acid lithium or cobalt and tungsten dust. Four patients all complained of intermittent cough, chest tightness, or shortness of breath on exertion. High-resolution computed tomography scans presented bilateral ground-glass attenuation, consolidations, and/or reticular opacities with diffuse small nodules. Histologic findings showed that interstitial inflammation and fibrotic lesions distributed peribronchioles. The infiltrations by macrophages as well as visible multinucleated giant cells indicated giant cell interstitial pneumonia (GIP). Cobalt was detectable in the lung tissues of two patients measured by inductively-coupled plasma mass spectrometry. The first patient was diagnosed with cobalt-related interstitial lung disease (ILD), while the others were HMLD. GIP is the classic pathology of cobalt-related ILD or HMLD. One of the patients showed spontaneous remission after the cessation of exposure, while the other three recovered within 6-32 weeks after avoiding occupational exposure and using corticosteroids. At follow-up, all four patients showed no recurrence. A multidisciplinary diagnostic panel including occupational cobalt exposure evaluation is beneficial to recognize cobalt-related ILD or HMLD and to indicate the necessity of prevention.

Tungsten: an Emerging Toxicant, Alone or in Combination

PURPOSE OF REVIEW

Tungsten is an emerging environmental toxicant, yet our understanding of the potential risks of exposure on human health is still limited.

RECENT FINDINGS

In this review, we will discuss populations most at risk of exposure to high concentrations of tungsten. In addition, we will highlight what is known about the toxicity profile of tungsten compounds, based on epidemiological, in vitro, and in vivo studies, focusing on bone, immune, pulmonary, and cancer outcomes. Of note, emerging evidence indicates that tungsten can augment the effects of other stimulants, stressors, and toxicants. Of particular importance may be tungsten-cobalt mixtures that seem to be more toxic than either metal alone. This is important because it means that we cannot just evaluate the toxicity of tungsten in isolation. Finally, we still have limited information of how many of the in vitro and in vivo findings translate to human populations, so it will be important to conduct epidemiology studies in highly exposed populations to adequately address the potential risks of tungsten exposure on human health. Together, we discuss recent findings that support further investigation into the toxicities of tungsten alone and in combination with other metals.

Hard metal lung disease: a case series

Objective:

To describe diagnostic and treatment aspects of hard metal lung disease (HMLD) and to review the current literature on the topic.

Methods:

This was a retrospective study based on the medical records of patients treated at the Occupational Respiratory Diseases Clinic of the Instituto do Coração, in the city of São Paulo, Brazil, between 2010 and 2013.

Results:

Of 320 patients treated during the study period, 5 (1.56%) were diagnosed with HMLD. All of those 5 patients were male (mean age, 42.0 ± 13.6 years; mean duration of exposure to hard metals, 11.4 ± 8.0 years). Occupational histories were taken, after which the patients underwent clinical evaluation, chest HRCT, pulmonary function tests, bronchoscopy, BAL, and lung biopsy. Restrictive lung disease was found in all subjects. The most common chest HRCT finding was ground glass opacities (in 80%). In 4 patients, BALF revealed multinucleated giant cells. In 3 patients, lung biopsy revealed giant cell interstitial pneumonia. One patient was diagnosed with desquamative interstitial pneumonia associated with cellular bronchiolitis, and another was diagnosed with a hypersensitivity pneumonitis pattern. All patients were withdrawn from exposure and treated with corticosteroid. Clinical improvement occurred in 2 patients, whereas the disease progressed in 3.

Conclusions:

Although HMLD is a rare entity, it should always be included in the differential diagnosis of respiratory dysfunction in workers with a high occupational risk of exposure to hard metal particles. A relevant history (clinical and occupational) accompanied by chest HRCT and BAL findings suggestive of the disease might be sufficient for the diagnosis.

Objetivo:

Descrever aspectos relacionados ao diagnóstico e tratamento de pacientes com doença pulmonar por metal duro (DPMD) e realizar uma revisão da literatura.

Métodos:

Estudo retrospectivo dos prontuários médicos de pacientes atendidos no Serviço de Doenças Respiratórias Ocupacionais do Instituto do Coração, localizado na cidade de São Paulo, entre 2010 e 2013.

Resultados:

Entre 320 pacientes atendidos no período do estudo, 5 (1,56%) foram diagnosticados com DPMD. Todos os pacientes eram do sexo masculino, com média de idade de 42,0 ± 13,6 anos e média de tempo de exposição a metal duro de 11,4 ± 8,0 anos. Os pacientes foram submetidos a avaliação clinica, história ocupacional, TCAR de tórax, prova de função pulmonar, broncoscopia com LBA e biópsia pulmonar. Todos apresentaram distúrbio ventilatório restritivo. O achado de imagem à TCAR de tórax mais frequente foi de opacidades em vidro fosco (em 80%). Em 4 pacientes, o LBA revelou presença de células gigantes multinucleadas. Em 3, foi diagnosticada pneumonia intersticial por células gigantes na biópsia pulmonar. Houve o diagnóstico de pneumonia intersticial descamativa associada à bronquiolite celular em 1 paciente e de pneumonite de hipersensibilidade em 1. Todos foram afastados da exposição e tratados com corticoide. Houve melhora em 2 pacientes e progressão da doença em 3.

Conclusões:

Apesar de ser uma entidade rara, a DPMD deve ser sempre considerada em trabalhadores com risco ocupacional elevado de exposição a metais duros. A história clínica e ocupacional associada a achados em TCAR de tórax e LBA sugestivos da doença podem ser suficientes para o diagnóstico.

Cobalt related interstitial lung disease

Cobalt exposure in the hard metal and bonded diamond tool industry is a well-established cause of ILD. The primary theories regarding the underlying mechanism of cobalt related ILD include an immunologic mechanism and an oxidant injury mechanism. Cobalt related ILD may present in subacute and chronic forms and often has associated upper respiratory symptoms. The evaluation begins with a thorough occupational history and includes PFTs, HRCT, and bronchoalveolar lavage. HRCT findings are nonspecific and may resemble NSIP, UIP, sarcoidosis, or HP. The finding of cannibalistic multinucleated giant cells is diagnostic provided there is a history of exposure and appropriate changes on imaging; however, when these cells are not found on lavage, lung biopsy is required for diagnosis. Giant cell interstitial pneumonia is the classic pathologic pattern, but cobalt related ILD may also present with pathologic findings of UIP, DIP, or HP. When cobalt related ILD is suspected, removal from exposure is the most important step in treatment. Case reports suggest that treatment with steroids results in symptomatic, physiologic, and radiographic improvement.

Nanotoxicity: emerging concerns regarding nanomaterial safety and occupational hard metal (WC-Co) nanoparticle exposure

As the number of commercial and consumer products containing engineered nanomaterials (ENMs) continually rises, the increased use and production of these ENMs presents an important toxicological concern. Although ENMs offer a number of advantages over traditional materials, their extremely small size and associated characteristics may also greatly enhance their toxic potentials. ENM exposure can occur in various consumer and industrial settings through inhalation, ingestion, or dermal routes. Although the importance of accurate ENM characterization, effective dosage metrics, and selection of appropriate cell or animal-based models are universally agreed upon as important factors in ENM research, at present, there is no “standardized” approach used to assess ENM toxicity in the research community. Of particular interest is occupational exposure to tungsten carbide cobalt (WC-Co) “dusts,” composed of nano- and micro-sized particles, in hard metal manufacturing facilities and mining and drilling industries. Inhalation of WC-Co dust is known to cause “hard metal lung disease” and an increased risk of lung cancer; however, the mechanisms underlying WC-Co toxicity, the inflammatory disease state and progression to cancer are poorly understood. Herein, a discussion of ENM toxicity is followed by a review of the known literature regarding the effects of WC-Co particle exposure. The risk of WC-Co exposure in occupational settings and the updates of in vitro and in vivo studies of both micro- and nano-WC-Co particles are discussed.

In vitro inflammatory effects of hard metal (WC-Co) nanoparticle exposure

Identifying the toxicity of nanoparticles (NPs) is an important area of research as the number of nanomaterial-based consumer and industrial products continually rises. In addition, the potential inflammatory effects resulting from pulmonary NP exposure are emerging as an important aspect of nanotoxicity. In this study, the toxicity and inflammatory state resulting from tungsten carbide–cobalt (WC–Co) NP exposure in macrophages and a coculture (CC) of lung epithelial cells (BEAS-2B) and macrophages (THP-1) at a 3:1 ratio were examined. It was found that the toxicity of nano-WC–Co was cell dependent; significantly less toxicity was observed in THP-1 cells compared to BEAS-2B cells. It was demonstrated that nano-WC–Co caused reduced toxicity in the CC model compared to lung epithelial cell monoculture, which suggested that macrophages may play a protective role against nano-WC–Co-mediated toxicity in CCs. Nano-WC–Co exposure in macrophages resulted in increased levels of interleukin (IL)-1β and IL-12 secretion and decreased levels of tumor necrosis factor alpha (TNFα). In addition, the polarizing effects of nano-WC–Co exposure toward the M1 (pro-inflammatory) and M2 (anti-inflammatory) macrophage phenotypes were investigated. The results of this study indicated that nano-WC–Co exposure stimulated the M1 phenotype, marked by high expression of CD40 M1 macrophage surface markers.

Imaging of Occupational Lung Disease

Occupational lung diseases span a variety of pulmonary disorders caused by inhalation of dusts or chemical antigens in a vocational setting. Included in these are the classic mineral pneumoconioses of silicosis, coal worker's pneumoconiosis, and asbestos-related diseases as well as many immune-mediated and airway-centric diseases, and new and emerging disorders. Although some of these have characteristic imaging appearances, a multidisciplinary approach with focus on occupational exposure history is essential to proper diagnosis.

Two cases of hard metal lung disease showing gradual improvement in pulmonary function after avoiding dust exposure

We present herein two cases of hard metal lung disease (HMLD) with distinct pathological findings. Both cases showed gradual improvements in pulmonary function over a period of a few years (Case 1: 30 months; Case 2: 12 months) after the avoidance of dust exposure, while improvements on high-resolution computed tomography were modest. The increased lymphocytes and decreased CD4/CD8 ratio in BALF observed at initial diagnosis normalized after the avoidance of dust exposure in one case. To the best of our knowledge, this is the first report demonstrating continual follow-up of pulmonary function and radiographic findings, and a comparison of BALF findings before and after avoidance of hard metal dust exposure.

Occupational and environmental lung disease

Occupational and environmental lung disease remains a major cause of respiratory impairment worldwide. Despite regulations, increasing rates of coal worker's pneumoconiosis and progressive massive fibrosis are being reported in the United States. Dust exposures are occurring in new industries, for instance, silica in hydraulic fracking. Nonoccupational environmental lung disease contributes to major respiratory disease, asthma, and COPD. Knowledge of the imaging patterns of occupational and environmental lung disease is critical in diagnosing patients with occult exposures and managing patients with suspected or known exposures.

Acute inflammatory responses of nanoparticles in an intra-tracheal instillation rat model

Exposure to hard metal tungsten carbide cobalt (WC-Co) "dusts" in enclosed industrial environments is known to contribute to the development of hard metal lung disease and an increased risk for lung cancer. Currently, the influence of local and systemic inflammation on disease progression following WC-Co exposure remains unclear. To better understand the relationship between WC-Co nanoparticle (NP) exposure and its resultant effects, the acute local pulmonary and systemic inflammatory responses caused by WC-Co NPs were explored using an intra-tracheal instillation (IT) model and compared to those of CeO2 (another occupational hazard) NP exposure. Sprague-Dawley rats were given an IT dose (0-500 μg per rat) of WC-Co or CeO2 NPs. Following 24-hr exposure, broncho-alveolar lavage fluid and whole blood were collected and analyzed. A consistent lack of acute local pulmonary inflammation was observed in terms of the broncho-alveolar lavage fluid parameters examined (i.e. LDH, albumin, and macrophage activation) in animals exposed to WC-Co NP; however, significant acute pulmonary inflammation was observed in the CeO2 NP group. The lack of acute inflammation following WC-Co NP exposure contrasts with earlier in vivo reports regarding WC-Co toxicity in rats, illuminating the critical role of NP dose and exposure time and bringing into question the potential role of impurities in particle samples. Further, we demonstrated that WC-Co NP exposure does not induce acute systemic effects since no significant increase in circulating inflammatory cytokines were observed. Taken together, the results of this in vivo study illustrate the distinct differences in acute local pulmonary and systemic inflammatory responses to NPs composed of WC-Co and CeO2; therefore, it is important that the outcomes of pulmonary exposure to one type of NPs may not be implicitly extrapolated to other types of NPs.

Recurrent nitrofurantoin-induced giant cell interstitial pneumonia: Case report and literature review

Giant cell interstitial pneumonia (GIP) is a rare form of chronic interstitial pneumonia typically associated with hard metal exposure. Only two cases of GIP induced by nitrofurantoin have been reported in the medical literature. We are reporting a case of recurrent nitrofurantoin-induced GIP. Although extremely rare, GIP needs to be included in the differential diagnosis in patients with chronic nitrofurantoin use who present with respiratory illness.

Exploring the potential role of tungsten carbide cobalt (WC-Co) nanoparticle internalization in observed toxicity toward lung epithelial cells in vitro

Tungsten carbide cobalt (WC-Co) has been recognized as a workplace inhalation hazard in the manufacturing, mining and drilling industries by the National Institute of Occupational Safety and Health. Exposure to WC-Co is known to cause "hard metal lung disease" but the relationship between exposure, toxicity and development of disease remain poorly understood. To better understand this relationship, the present study examined the role of WC-Co particle size and internalization on toxicity using lung epithelial cells. We demonstrated that nano- and micro-WC-Co particles exerted toxicity in a dose- and time-dependent manner and that nano-WC-Co particles caused significantly greater toxicity at lower concentrations and shorter exposure times compared to micro-WC-Co particles. WC-Co particles in the nano-size range (not micron-sized) were internalized by lung epithelial cells, which suggested that internalization may play a key role in the enhanced toxicity of nano-WC-Co particles over micro-WC-Co particles. Further exploration of the internalization process indicated that there may be multiple mechanisms involved in WC-Co internalization such as actin and microtubule based cytoskeletal rearrangements. These findings support our hypothesis that WC-Co particle internalization contributes to cellular toxicity and suggest that therapeutic treatments inhibiting particle internalization may serve as prophylactic approaches for those at risk of WC-Co particle exposure.

An observational study of giant cell interstitial pneumonia and lung fibrosis in hard metal lung disease

BACKGROUND

Hard metal lung disease has various pathological patterns including giant cell interstitial pneumonia (GIP) and usual interstitial pneumonia (UIP). Although the UIP pattern is considered the prominent feature in advanced disease, it is unknown whether GIP finally progresses to the UIP pattern.

OBJECTIVES

To clarify clinical, pathological and elemental differences between the GIP and UIP patterns in hard metal lung disease.

METHODS

A cross-sectional study of patients from 17 institutes participating in the 10th annual meeting of the Tokyo Research Group for Diffuse Parenchymal Lung Diseases, 2009. Nineteen patients (seven female) diagnosed with hard metal lung disease by the presence of tungsten in lung specimens were studied.

RESULTS

Fourteen cases were pathologically diagnosed as GIP or centrilobular inflammation/fibrosing. The other five cases were the UIP pattern or upper lobe fibrosis. Elemental analyses of lung specimens of GIP showed tungsten throughout the centrilobular fibrotic areas. In the UIP pattern, tungsten was detected in the periarteriolar area with subpleural fibrosis, but no association with centrilobular fibrosis or inflammatory cell infiltration. The GIP group was younger (43.1 vs 58.6 years), with shorter exposure duration (73 vs 285 months; p<0.01), lower serum KL-6 (398 vs 710 U/mL) and higher lymphocyte percentage in bronchoalveolar lavage fluid (31.5% vs 3.22%; p<0.05) than the fibrosis group.

CONCLUSIONS

The UIP pattern or upper lobe fibrosis is remarkably different from GIP in distribution of hard metal elements, associated interstitial inflammation and fibrosis, and clinical features. In hard metal lung disease, the UIP pattern or upper lobe fibrosis may not be an advanced form of GIP.

Elemental analysis of occupational and environmental lung diseases by electron probe microanalyzer with wavelength dispersive spectrometer

Occupational and environmental lung diseases are a group of pulmonary disorders caused by inhalation of harmful particles, mists, vapors or gases. Mineralogical analysis is not generally required in the diagnosis of most cases of these diseases. Apart from minerals that are encountered rarely or only in specific occupations, small quantities of mineral dusts are present in the healthy lung. As such when mineralogical analysis is required, quantitative or semi-quantitative methods must be employed. An electron probe microanalyzer with wavelength dispersive spectrometer (EPMA-WDS) enables analysis of human lung tissue for deposits of elements by both qualitative and semi-quantitative methods. Since 1993, we have analyzed 162 cases of suspected occupational and environmental lung diseases using an EPMA-WDS. Our institute has been accepting online requests for elemental analysis of lung tissue samples by EPMA-WDS since January 2011. Hard metal lung disease is an occupational interstitial lung disease that primarily affects workers exposed to the dust of tungsten carbide. The characteristic pathological findings of the disease are giant cell interstitial pneumonia (GIP) with centrilobular fibrosis, surrounded by mild alveolitis with giant cells within the alveolar space. EPMA-WDS analysis of biopsied lung tissue from patients with GIP has demonstrated that tungsten and/or cobalt is distributed in the giant cells and centrilobular fibrosing lesion in GIP. Pneumoconiosis, caused by amorphous silica, and acute interstitial pneumonia, associated with the giant tsunami, were also elementally analyzed by EPMA-WDS. The results suggest that commonly found elements, such as silicon, aluminum, and iron, may cause occupational and environmental lung diseases.

Interstitial lung diseases-can pathologists arrive at an etiology-based diagnosis? A critical update

Interstitial lung diseases (ILD) encompass a group of diseases with a wide range of etiologies and a variety of tissue reactions within the lung. In many instances, a careful evaluation of the tissue reactions will result in a specific diagnosis or at least in a narrow range of differentials, which will assist the clinician to arrive at a definite diagnosis, when combining our interpretation with the clinical presentation of the patient and high-resolution computed tomography. In this review, we will exclude granulomatous pneumonias as well as vascular diseases (primary arterial pulmonary hypertension and vasculitis); however, pulmonary hypertension as a complication of interstitial processes will be mentioned. Few entities of pneumoconiosis presenting as an interstitial process will be included, whereas those with granulomatous reactions will be excluded. Drug reactions will be touched on within interstitial pneumonias, but will not be a major focus. In contrast to the present-day preferred descriptive pattern recognition, it is the author's strong belief that pathologists should always try to dig out the etiology from a tissue specimen and not being satisfied with just a pattern description. It is the difference of sorting tissue reactions into boxes by their main pattern, without recognizing minor or minute reactions, which sometimes will guide one to the correct etiology-oriented interpretation. In the author's personal perspective, tissue reactions can even be sorted by their timeliness, and therefore, ordered by the time of appearance, providing an insight into the pathogenesis and course of a disease. Also, underlying immune mechanisms will be discussed briefly as far as they are essential to understand the disease.

A case of hard metal lung disease resembling a hypersensitive pneumonia in radiological images

A 42-year-old man was admitted to our hospital because of exertional dyspnea. He had worked as a metal grinder for 3 years, but had quit his job 1 month before admission. Chest radiography and high-resolution computed tomography showed diffuse ground-glass opacities like hypersensitivity pneumonitis shadows. The results of high-energy dispersion X-ray microanalysis indicated that the patient had hard metal pneumoconiosis associated with tungsten. Since the histological changes distributed terminal to respiratory bronchiole and surrounding alveoli, and macrophages engulfed black granules within the alveoli, in absence of giant cells, we considered this case to be a type of hypersensitivity pneumonitis of hard metal lung.