Article Outline
Interstitial lung disease (ILD) is a general term that includes a variety of chronic lung disorders. When an individual has ILD, the lung is affected in 3 ways. First, the lung tissue is damaged in some known or unknown way. Second, the alveolar walls become inflamed, and third, the interstitium becomes scarred and stiff. Patients with different types of ILD may have the same symptoms but their symptoms may vary in severity. Their chest radiographs may appear identical. The course of these diseases is unpredictable. Some of the diseases improve with medication if treated when inflammation occurs. Chances of recovery or the disease getting worse depend on the cause and severity of the disease when it was first diagnosed. Computed tomography (CT) scanning has become a frontline test in the diagnosis of ILD and can often suggest a specific diagnosis with a high degree of certainty when the CT findings are combined with clinical history. Find out your ILD intelligence quotient by answering the following questions. Then, read the articles in this issue to learn more about ILD. I thank Dr Kanne and all authors who contributed to this issue. I know it will be a valuable resource to anyone who deals with ILD in their practice.
1.What is the most prevalent type of idiopathic ILD?
A.Usual interstitial pneumonitis (UIP)
B.Nonspecific interstitial pneumonitis (NSIP)
C.Acute interstitial pneumonitis (AIP)
D.Desquamative interstitial pneumonitis (DIP)
E.Cryptogenic organizing pneumonitis (COP)
2.What ILD affects only women of childbearing age?
A.Langerhans cell histiocytosis
B.Lymphangioleiomyomatosis
C.Asbestosis
D.Silicosis
E.Usual interstitial pneumonitis
3.Which of the following pulmonary tests is the most invasive?
A.Pulmonary function tests (PFTs)
B.High-resolution computerized tomography (HRCT) scan
C.Transbronchial biopsy
D.Bronchoalveolar lavage
E.Video-assisted thoracoscopic surgery
4.Which of the following drugs used to treat usual interstitial pneumonitis is classified as an antioxidant drug?
A.Acetylcysteine
B.Azathioprine
C.Colchicine
D.Cyclophosphamide
E.Pirfenidone
5.What is the main symptom of idiopathic pulmonary fibrosis?
A.Productive cough
B.Shortness of breath
C.Fever
D.Chest pain
6.Which of the following is a common radiologic feature of nonspecific interstitial pneumonitis (NSIP)?
A.Subpleural sparing
B.Upper lobe predominance
C.Asymmetry of findings
D.Unilateral distribution
E.Extensive honeycombing
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Answers
1.A, Usual interstitial pneumonitis: Some of the known causes of ILD include exposure to toxins or pollutants (eg, silica dust, asbestos fibers, hard metal dust, chemical fumes, and ammonia or chlorine gases), infections, radiation, drugs, and other medical conditions, such as collagen vascular diseases.1 Interstitial lung diseases without a known cause are considered a subset of interstitial lung disease and are grouped together under the label idiopathic interstitial lung disease. UIP is the most prevalent type of idiopathic ILD. Although the idiopathic diseases have certain features in common, each also has unique characteristics.
2.B, Lymphangioleiomyomatosis: Lymphangioleiomyomatosis (LAM) is a rare disorder in which muscle cells invade and eventually obstruct the airways and blood and lymph vessels in the lung; further, it affects only women of childbearing age.1
3.E, Video-assisted thoracoscopic surgery: When less invasive tests do not yield a specific diagnosis, a thoracic surgeon may perform video-assisted thoracoscopic surgery (VATS). In this procedure, an endoscope is inserted through a small incision between the ribs, allowing the surgeon to view the lungs on a video monitor. Surgical instruments are then inserted through another incision, and the surgeon removes thumbnail-sized tissue samples from 2 or 3 sites in the lungs.1 Pulmonary function tests are a noninvasive way to measure the amount of gases exchanged across the alveolar/capillary membrane. Transbronchial biopsy is performed on an outpatient using local anesthesia and involves bronchoscopy combined with removal of one or more tissue samples the size of a pin. In bronchoalveolar lavage, saline is injected through a bronchoscope into a section of lung and then immediately suctioned out. The withdrawn solution contains alveolar cells.
4.A, Acetylcysteine: Oxidation is a natural process that leads to cell and tissue damage. The process may play a role in the development of scarring in the lungs. One trial of the antioxidant acetylcysteine found moderate improvements in lung function in people with idiopathic pulmonary fibrosis, though no significant changes were seen in mortality rates.1 Corticosteroids (anti-inflammatory drugs) are the initial treatment of choice for ILD but they help a minority of people with the disease and when they do help, the benefits are usually temporary. Azathioprine, normally used to prevent organ rejection after a transplant, and the anticancer drug cyclophosphamide are cytotoxic drugs that may be used to treat ILD. Colchicine and pirfenidone are antifibrotics that are sometimes used to help reduce the development of scar tissue. In clinical studies, they showed promise for slowing the progression of lung damage without suppressing the immune system, but real-world results have generally been disappointing.1
5.B, Shortness of breath: Shortness of breath is the main symptom of idiopathic pulmonary fibrosis. It is a symptom of many types of lung disease and is therefore nonspecific. It may first appear during exercise and progress to the point where any exertion is impossible. Eventually, the patient may become short of breath even at rest.2 Another common symptom associated with ILD is dry cough. Fever and chest pain can be present in the event of superimposed infection.
6.A, Subpleural sparing: NSIP was initially thought to involve primarily the lung periphery. However, subsequent studies have shown NSIP to have a peripherally predominant pattern in only 38%-74% of patients.3, 4 In the experience of Kligerman et al, lower lobe peribronchovascular predominance, with subpleural sparing, is common in NSIP.5 The distribution of NSIP is usually symmetric and bilateral. Unilateral findings are exceedingly rare in NSIP and should suggest an alternate diagnosis.5 Ground-glass opacity is present in nearly all cases. The absence of ground-glass opacity in addition to extensive honeycombing helps eliminate the diagnosis of NSIP.5
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References
- Mayo Clinic Staff. Interstitial lung disease. http://www.mayoclinic.com/print/interstitial-lung-disease/DS00592/Method=print&DS
- American Lung Association. Interstitial lung disease and pulmonary fibrosis. http://www.lungusa.org/site/apps/nlnet/content3.aspx?c=dvLUK9O0E&b=2060161&content_id={4350F20F-98E4-403B-A33B-68B20A3C2FBA}¬oc=1&gclid=CPvU18fSpZkCFQMnGgodWA3oqQ
- MacDonald SL, Rubens MB, Hansell DM, et al. Nonspecific interstitial pneumonia and usual interstitial pneumonia: comparative appearances at and diagnostic accuracy of thin-section CT. Radiology. 2001;221:600–605
- Johkoh T, Muller NL, Colby TV, et al. Nonspecific interstitial pneumonia: correlation between thin-section CT findings and pathologic subgroups in 55 patients. Radiology. 2002;225:199–204
- Kligerman SJ, Groshong S, Brown KK, et al. Nonspecific interstitial pneumonia: radiologic, clinical, and pathologic considerations. Radiographics. 2009;29:73–87
