Ground-glass computed tomography pattern in chronic beryllium disease: pathologic substratum and evolution

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.

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.

Radiological approach to interstitial lung disease: a guide for the nonradiologist

Articles in the past have described the radiological appearances of different interstitial lung diseases (ILDs) in varying levels of detail. However, these articles have generally been written for radiologists with a background in basic chest computed tomography (CT) interpretation. This article summarizes a basic approach for diagnosing ILDs on high-resolution CT (HRCT) for the nonradiologist clinician and discusses the most common HRCT features of common ILDs.

Chronic beryllium disease: computed tomographic findings

Chronic beryllium disease is a rare multisystem granulomatous disease predominantly involving the lungs and resulting from an immunologic response to long-term occupational exposure. Computed tomography of the chest reveals important lung parenchymal and mediastinal findings and plays an important role in the diagnosis and follow-up assessment of patients with chronic beryllium disease. Its significance lies in the exact localization and evaluation of the extent of lesions. We present an overview of the subject and a pictorial review of the spectrum of computed tomographic features of beryllium disease.

Immunology of chronic beryllium disease

PURPOSE OF REVIEW

This review discusses the immunology of chronic beryllium disease. It addresses the importance of the interaction between class II molecules and the T cells that recognize beryllium, along with the subsequent immune response that results in sensitization and disease, and genetic factors leading to variation in this response.

RECENT FINDINGS

HLA-DPB1 with a glutamic acid at amino acid position 69 (Glu69) confers increased risk of beryllium sensitization and is not specific for chronic beryllium disease. The degree of negative surface charge of the molecule may increase risk of chronic beryllium disease but not sensitization. In the absence of Glu69, HLA-DRB1 alleles may function in beryllium presentation, increasing the risk of chronic beryllium disease. The T-cell response as assessed by the beryllium lymphocyte proliferation test is dependent on central memory T-cells, while Th1 cytokine secretion leading to granulomatous inflammation and chronic beryllium disease is dependent on the activity of effector memory T cells. Polymorphisms in cytokine genes, such as the TGF-beta1 gene, also affect the risk of chronic beryllium disease and more severe disease.

SUMMARY

The current diagnostic criteria for sensitization and chronic beryllium disease rely on the beryllium lymphocyte proliferation test. By understanding the novel immunologic mechanisms and genetic factors associated with sensitization and chronic beryllium disease, we may improve our ability to detect beryllium health effects with new diagnostics, and hopefully refine therapies for disease.

Bérylliose Pulmonaire Chronique : un modèle d’interaction entre environnement et prédisposition génétique (1re partie)

INTRODUCTION

The physico-chemical properties of beryllium (Be) are crucial for high technology industries. The inhalation of beryllium may cause, in certain individuals, a specific sensitisation (BeS) and lead, in some of them, to a pulmonary granulomatosis called chronic pulmonary berylliosis (CPB).

BACKGROUND

Although there is no linear relationship between the level of exposure to Be and the risks of BeS and CPB, the highest exposures are associated with an increased risk. The specific influences of the chemical composition, the solubility and different types of Be on the risk of BeS an CPB are poorly understood. Insoluble particles of small diameter are probably associated with an increased risk. Many studies have reported the role of a genetic predisposition in the risk of BeS and CPB. At present the role of HLA-DPB1 Glu69 in sensitisation to Be is the best studied.

CONCLUSION

Sensitisation to Be and CPB result from the combination of exposure and predisposing genetic polymorphisms. CPB is a model for the understanding of the pathology of certain ideopathic pulmonary granulomatoses such as sarcoidosis.

Bérylliose pulmonaire chronique (2e partie)

INTRODUCTION

Chronic beryllium disease (CBD) is an occupational lung disease caused by the inhalation of beryllium dust, fumes or metallic salts.

CURRENT DATA

Beryllium affects the lungs via particles deposited in the pulmonary alveoli. These are ingested by alveolar macrophages which act as antigen presenting cells to CD4+ T lymphocytes. T lymphocytes proliferate in response to beryllium antigens and combined with macrophages produce numerous epithelioid granulomas with the release of inflammatory cytokines (IFNgamma, IL-2, TNFalpha and IL6) and growth factors. Beryllium induces macrophage apoptosis which reduces its clearance from the lung which in turn contributes to the host's continual re-exposure and thus a chronic granulomatous disorder. Pulmonary granulomatous inflammation is the primary manifestation of CBD, but the disease occasionally involves other organs such as the liver, spleen, lymph nodes and bone marrow. The clinical, radiological, and histopathological features of CBD can be difficult to distinguish from sarcoidosis. The Beryllium lymphocyte proliferation test (BeLPT) demonstrates a beryllium specific immune response, confirms the diagnosis of CBD, and excludes sarcoidosis.

CONCLUSIONS AND PERSPECTIVES

CBD provides a human model of pulmonary granulomatous disease produced by an occupational exposure, occurring more frequently in those with a genetic pre-disposition. It can be differentiated from sarcoidosis by specific immunological testing.

Imaging of unusual diffuse lung diseases

PURPOSE OF REVIEW

Computed tomography scans are commonly used in imaging lung diseases. As more information accumulates, patterns of rare or new diseases on CT scans are being increasingly reported. Several pulmonary diseases have distinguishing features, which are better delineated on high resolution CT scans than plain chest radiographs. The radiographic features of unusual diffuse lung diseases published in the past two years are described.

RECENT FINDINGS

Severe acute respiratory syndrome generally manifests as focal or diffuse bilateral areas of consolidation on chest radiography and reticulation with ground-glass attenuation commonly seen on CT scans. A normal HRCT rules out the diagnosis of Pneumocystis carinii pneumonia while a normal chest radiograph does not. Immunocompromised patients without AIDS, who have CMV pneumonia, generally demonstrate a combination of ground-glass attenuation, air-space consolidation, and small nodules on HRCT. Nodules less than 10 mm in size in immunocompromised patients are highly suggestive of viral infections. Bronchial wall thickening on HRCT associated with cavitating nodules is suggestive of Wegner granulomatosis in the appropriate clinical setting. Small cysts may be seen in a minority of patients with subacute hypersensitivity pneumonitis and centrilobular emphysema in chronic farmer's lung. Reversed halo sign has a high specificity for cryptogenic organizing pneumonia. The triad of ground-glass opacities, ill-defined centrilobular nodules and cysts and focal areas of air trapping is highly suggestive of subacute hypersensitivity pneumonitis.

SUMMARY

Familiarizing with radiographic and CT scan patterns may help the clinician to exclude certain diagnoses and narrow the differential diagnosis for others.