A Review of Restrictive Lung Disease for the Physician Assistant Exam
A restrictive pattern on a pulmonary function test (PFT) is a reduced diffusion capacity of the lungs for carbon dioxide. The Physician Assistant Exam (PANCE) will question you about these conditions, so you should review lung disease caused by occupational exposure, interstitial lung disease (ILD), and granulomatous diseases, including sarcoidosis.
Occupational exposure to the dust of various materials is a significant cause of pulmonary problems. You should review these dust-related lung diseases — which are various types of pneumoconiosis — including lung disorders related to exposure to silica, asbestos, and coal.
Silicosis is caused by inhaling dust from silica. People who are exposed to silica, including stoneworkers and sandblasters, are at risk. Here are some key points about silicosis:
A high-yield chest radiograph finding is eggshell calcifications. This refers to hilar adenopathy, which may be calcified.
The treatment is generally supportive, including antibiotics when needed and steroids for superimposed inflammation.
People with silicosis are at greater risk for the development of tuberculosis (so-called silicotuberculosis).
Asbestosis is caused by inhalation of asbestos dust, which over time causes inflammation and fibrotic changes (scarring) in the lung. Anyone who has been involved in construction work, especially working on older buildings where asbestos was in the walls and part of the insulation, is at risk. Here are the key points about asbestosis:
Cigarette smoking is really bad if you have asbestosis because asbestosis increases the risk of lung cancer. It can also exponentially increase the damage smoking does to the lungs.
Asbestosis is associated with the development of malignant melanoma.
Important chest radiograph findings include increased interstitial lung markings, pleural thickening, and pleural plaques.
Coal worker’s pneumoconiosis
Coal worker’s pneumoconiosis, as the name suggests, involves coal miners who develop lung problems due to inhalation of coal dust. This causes significant inflammatory and fibrotic changes in the lung. The key point concerning coal worker’s pneumoconiosis is that a chest radiograph demonstrates nodules in the upper lung zones.
Caplan’s syndrome is a combination of pneumoconiosis and rheumatoid arthritis (RA). The characteristic finding is long nodules on a routine chest radiograph.
Interstitial lung disease
Interstitial lung disease (ILD) comes in several types. It’s usually of an insidious onset, with progressive shortness of breath and exertional dyspnea. ILD refers to the inflammation of the lung parenchyma, which surrounds the lung alveoli.
The cause of ILD isn’t known; it’s thought that an abnormal immune response in the lungs may play a role. It may be a side effect of medication, including the chemotherapy agent busufan (Myleran) and the antiarrythmic agent amiodarone (Cordarone). You see it in many rheumatologic conditions, including rheumatoid arthritis (RA). Many cases of ILD are termed idiopathic because the underlying cause is unknown.
Here are the key points concerning ILD:
Many of the subtypes of ILD are defined by the histology that’s found on lung biopsy, the gold standard for diagnosing ILD. Common types include usual interstitial pneumonia (UIP) and desquamative interstitial pneumonia (DIP).
A chest radiograph shows interstitial infiltrates in a reticulonodular pattern.
The diagnosis can be confirmed with a high-resolution CT scan. With ILD, you can often see a radiologic finding of honeycombing.
The role of steroids and other immunosuppressive agents in treating ILD isn’t yet fully defined. The overall prognosis of ILD is not very good.
Cryptogenic organizing pneumonia is an uncommon type of ILD, diagnosed via lung biopsy. It affects the small airways and alveoli. It’s been linked to many medical conditions, including infections and connective tissue diseases. BOOP can be very steroid responsive. If you see a PANCE question about BOOP, think treatment with steroids. It actually responds well to treatment.
Sarcoidosis: Granulomatous disease
Granulomatous diseases come in many forms, but the one that you see most on the PANCE is sarcoidosis. Sarcoidosis is a noncaseating granulomatous disease that can affect multiple organs, including the lungs, liver, eyes, and skin. Here are some key points concerning sarcoidosis:
Clinical presentation consists of shortness of breath (SOB) and cough. Sarcoidosis usually has an insidious onset.
The lungs are the most common site of involvement.
Common lab findings can include an elevated erythrocyte sedimentation rate (ESR), an elevated angiotensin converting enzyme (ACE) level, and hypercalcemia.
You may see kidney stones, an elevated 24-hour urinary calcium excretion, and tubulointerstitial disease.
The classic chest radiograph finding is bilateral hilar lymphadenopathy. Other possible findings include bilateral pulmonary infiltrates.
Besides sarcoidosis, several other conditions can cause bilateral hilar lymphadenopathy on a chest radiograph. They include silicosis, beryliosis, fungal diseases, and lymphoma.
You need a lung biopsy to confirm the diagnosis of sarcoidosis.
The treatment of choice is steroids, and sarcoidosis is very responsive to treatment.