A 32-year-old man is seen in your clinic for progressive dyspnea on exertion and nonproductive cough for 1 year. Other symptoms include general malaise and some unintentional weight loss. He denies any hemoptysis or chest pain. He immigrated to the United States 2 months ago from Turkey. He stopped smoking 8 months ago. In Turkey he worked for the past 5 years in a factory that sandblasted denim jeans for that “already worn” look. He has no other medical history and denies significant family history.
On exam his vital signs are normal including a respiratory rate of 16 bpm. His entire chest exam is normal, without any increase in adventitial sounds or crackles. The remainder of the exam is normal.
A chest X-ray reveals few, subcentimeter, round nodules in both upper lobes.
Which of the following statements is true?
A. Pleural plaques are commonly seen on CXR.
B. Life expectancy is usually unaffected in these patients.
C. The patient has an increased risk of tuberculosis infection.
D. Treatment with high dose corticosteroids is usually very effective.
E. There was an exposure to the causative agent within the last one year.
Answer: C – The patient has an increased risk of tuberculosis infection.
Key Point:Recognize the clinical features of the various occupational lung diseases, including silicosis.
Know that silicosis is associated with an increased risk for tuberculosis.
Recognize that thymomas are associated with a wide variety of paraneoplastic disorders, the most common of which is myasthenia gravis.
Discussion:Occupational lung diseases are caused by exposure of the lungs to irritating or toxic substances, like silica dust in the case of silicosis. Exposure to silica dust can occur in any occupation or activity that involves disruption of the earth’s surface rock or uses silica/sand in the process.
Acute silicosis may occur relatively soon (weeks) after exposure to high concentrations of silica and is characterized by symptoms, such as cough, weight loss, fatigue and pleuritic pain. Crackles can be detected on exam. Chronic silicosis on the other hand develops after long term exposure (multiple years) and may be asymptomatic or involve cough and dyspnea without crackles on exam.
The chest X-ray findings range from the nodules mentioned in the question stem to progressive massive fibrosis.
Silicosis has been associated with alterations in immune function and an increased risk of certain autoimmune conditions (SLE, RA, e.g.). It also is associated with an increased risk for tuberculosis.
Although there are no proven therapies for silicosis, and steroids have nottreatment is based on relieving symptoms of dyspnea and cough and vigilance for infections. Life expectancy is much shorter and lung transplantation should be considered for the appropriate patients.
Leung CC, Yu IT, Chen W. Silicosis. Lancet. 2012 May 26;379(9830):2008-18.
Bakan ND, Özkan G, Çamsari G, Gür A, Bayram M, Açikmeşe B, Çetinkaya E. Silicosis in denim sandblasters. Chest. 2011 Nov;140(5):1300-4