Silica and silicate mineral dust inhalation can cause a variety of histopathological changes in the lungs and pleura. These include pulmonary silicotic nodules, interstitial infiltrate, fibrosis, and pleural thickening. Pleural effusion is an extremely rare presentation of silicosis. To our best knowledge, there have been only 2 cases of silicosis with pleural effusion reported in medical literature. Herein, we describe a case of a 77-year-old male with almost 50 years’ history of occupational silica exposure. He presented with a 4-week history of exertional shortness of breath. He is a lifetime nonsmoker, with no known other significant pulmonary disease. He had chest X-ray which showed a right lung infiltrate and bilateral pleural thickening and effusion. Chest CT showed moderate-sized bilateral pleural effusion and thickening with multiple bilateral intrapulmonary nodules seen. He had undergone extensive workup and was diagnosed with silicosis.
Various pleural involvements such as pleural thickening and progressive multifocal fibrosis (PMF) associated pleural invaginations are well-recognized complications associated with silicosis, particularly advanced pulmonary silicosis. However, pleural effusion is not a well-recognized finding in patients with silicosis. To the best of our knowledge, there have been only 2 cases reported in the medical literature that described pulmonary silicosis presented with pleural effusion. Herein, we describe a case of a 77-year-old gentleman who presented with shortness of breath and bilateral pleural effusion. The patient had undergone extensive workup and was diagnosed with pulmonary silicosis.
A 77-year-old gentleman with history of coronary artery disease, diabetes mellitus, and hypertension presented to the emergency department with worsening shortness of breath. He reported that he has been having some chronic baseline dyspnea on exertion which has been stable until 4-5 days prior to his presentation when it started to get worse with simple tasks such as getting dressed and showering. He denied any cough, sputum production, hemoptysis, paroxysmal nocturnal dyspnea, orthopnea, leg swelling, fever, chills, weight loss, or night sweating. He is a lifetime nonsmoker, with no other significant pulmonary history other than his occupational exposure. He had worked for at least 50 to 60 years carving and grinding stones, including granite and numerous other stones. Although he has been wearing a respirator for a large part of his more adult life, there was quite some time, including numerous years, where he wore no respiratory protection whatsoever. He has no tubercular risk factors other than silica exposure. There was no history of TB exposure. His past medical history is notable for coronary artery disease, diabetes, chronic kidney disease, and hypertension. There was no family history of lung cancer. On examination, he was afebrile and tachypneic with respiratory rate of 30. His oxygen saturation was 95% on room air at rest. On chest exam, he had signs of bilateral pleural effusion. Pertinent lab studies showed WBC count of 9 k/
Chest X-ray showed a right lung infiltrate and moderate right pleural effusion, small left pleural effusion, bilateral small irregular opacities, and pleural thickening.
Chest CT showed moderate-sized bilateral pleural effusion and thickening with pulmonary nodules. There is mild interstitial fibrosis. There are multiple bilateral intrapulmonary nodules seen. Some of the nodules are pleural-based. A few nodules do have a small amount of associated calcification.
Lung biopsy showed a silicotic nodule within lung parenchyma composed mainly of bundles of interlacing collagen. There is minimal inflammatory reaction.
Lung biopsy underpolarized microscopy showing bright white silica crystals of varying sizes.
Silicosis is an occupational lung disease caused by inhalation of free crystalline silicon dioxide or silica. The pulmonary silicosis is a well-known occupational lung disease caused by silica inhalation; however, new cases of pulmonary silicosis are still seen in clinical practice. Phagocytosis of crystalline silica in the lung causes lysosomal damage, activating the NALP3 inflammasome and triggering the inflammatory cascade with subsequent fibrosis [
Occupational silicosis has both pulmonary and extrapulmonary manifestations. Involvement of pleura is well described in pulmonary silicosis. Various pleural involvements can occur especially in advanced pulmonary fibrosis [
Diagnosis of silicosis generally relies on 3 key elements: a history of substantial exposure to silica dusts with appropriate latency from the time of first exposure, compatible radiological features, and exclusion of other competing diagnoses, such as miliary tuberculosis, fungal infections, sarcoidosis, idiopathic pulmonary fibrosis, other interstitial lung diseases, and primary or secondary lung cancers [
As mentioned above, pleural involvement in silicosis is well recognized especially in advanced pulmonary silicosis. However, pleural silicosis is still less common and less emphasized in medical literature than asbestosis as an occupational lung disease that is associated with pleural plaque, pleural effusion, and diffuse pleural thickening [
Summary of the reported cases of silicosis presenting with pleural effusion.
Case | Al-Kassimi’s case [ |
Zeren et al.’s case [ |
Our case |
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Age/sex | 70-year-old male | 57-year-old male | 77-year-old male |
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Occupation | Well digging, no more exposure | Plumbing fixture factory where he sprayed glazing compound, still exposed | Carving and grinding stones, no more exposure |
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Occurrence of pleural effusion in relation to time of silica exposure | More than 40 years | 32 years | More than 50 years |
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Onset of symptoms | Insidious | Subacute | Acute on chronic |
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Presenting symptoms | Shortness of breath | Shortness of breath, pleuritic chest pain, and fever | Shortness of breath |
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Radiographic changes of patient regarding silicosis | Chest X-ray showed bilateral interstitial shadowing more pronounced in the upper zones with massive pulmonary fibrosis as well as right pleural effusion (simple silicosis) | The chest X-ray and CT scans showed thickening of the left pleura consistent with a chronic process and a small right pleural effusion (simple silicosis) | The chest X-ray and CT scans showed bilateral pleural effusion and thickening with bilateral small irregular opacities (simple silicosis) |
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Transbronchial biopsy | Birefringent particles compatible with silicosis; hyperplasia of mesothelial cells | Macrophage containing birefringent particles; hyperplasia of mesothelial cells | Histiocytes containing refractile foreign material, consistent with silicosis; hyperplasia of mesothelial cells |
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Pleural fluid analysis | Exudative pleural effusion with high LDH | Not reported | Exudative pleural effusion with high LDH |
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Treatment & outcomes | Chemical pleurodesis; no recurrence in 3.5 years | Patient changes his job and his symptoms spontaneously resolved, resolved in 1 month, no recurrence in 3 years | Mechanical pleurodesis; no recurrence in 12 months |
Arakawa et al. conducted a retrospective study on the images of 110 patients who had an autopsy-proven silicosis. They found that pleural effusion is present in 35% of the patients studied. Sixty-eight percent (26 of 38) of the patients with pleural effusion had possible/probable cause for their effusion that was not silicosis (pneumonia, cardiac failure, hypoalbuminemia, pneumothorax, and malignancy) and only 11% of the silicosis patients had pleural effusion that is thought to be related to silicosis (no other causes have been found) [
This patient met diagnostic criteria for pulmonary silicosis mentioned above in terms of his job-related prolonged exposure to silica, bilateral pulmonary nodules on both CXR and CT scan, and absence of other alternative conditions such as primary or secondary malignancies, TB, or fungal infections. This patient likely had chronic silicosis given his remote history of silica exposure and his chronic history of dyspnea. Probably, the moderate-sized pleural effusion is what makes his shortness of breath worsen and present in acute pattern as we ruled out all possible infectious causes.
Different pleural disease can occur in silicosis particularly in advanced stages. Although pleural effusion is unusual in silicosis it is a possible cause if infectious, malignant, cardiovascular, renal, and connective tissue disease causes have been ruled out.
This paper does not contain any studies with human participants performed by any of the authors.
The authors declare that they have no relevant conflict of interests for this case.
The authors would like to thank Dr. Melnick Jeffrey from the radiology department for helping them acquire appropriate images.