(Chest. 2000;118:1198-1201.)
© 2000
American College of Chest Physicians
54-Year-Old Man With Dyspnea, Cough, and Hypoxemia*
Marvin I. Schwarz, MD, FCCP
*
From the ACCP-SEEK program, reprinted with permission. Items are selected by Department Editors Richard S. Irwin, MD, FCCP, and John G. Weg, MD, FCCP. For additional information about the ACCP-SEEK program, phone 1-847-498-1400.
Correspondence to: Marvin I. Schwarz, MD, FCCP, Pulmonary Sciences and Critical Care Medicine, University of Colorado Health Sciences Center, 4200 E. 9th Ave, Box C272, Denver, CO 80262; e-mail: Marvin Schwarz{at}UCHSC.edu
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Introduction
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A 54-year-old
man has developed gradual onset of dyspnea and nonproductive cough over
the past 6 months. He was an avid rock climber and long-distance
runner; now, he is unable to perform either of these activities. He was
first referred to a cardiologist, who found the results of the
following tests to be normal: ECG, exercise stress test, and cardiac
catheterization. His medical history is nonrevealing. He has not smoked
for the past 10 years.
Physical examination reveals a healthy, muscular man who is
comfortable at rest. His vital signs are normal. Lung auscultation
reveals bibasilar end-expiratory crackles. His extremities are not
edematous or clubbed. The remainder of the physical examination
is normal.
The CBC count, electrolytes, BUN, creatinine, liver function tests, and
urinalysis are normal. An arterial blood gas measurement, with the
patient breathing ambient air, shows a PO2 of
40 mm Hg; PCO2, 36 mm Hg; and pH, 7.48. The
chest radiograph and high-resolution CT scan are shown in Figures 1
,
2
.
Based on the above information, which of the following is the most
likely diagnosis?
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Figure 2.. Initial high-resolution CT indicating
the "crazy paving" pattern consisting of polygonal lines
representing thickened intralobular septa. There is also ground-glass
density.
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A. Alveolar proteinosis
B. Lymphangitic carcinomatosis
C. Hypersensitivity pneumonitis
D. Bronchiolitis obliterans organizing pneumonia
E. Desquamative interstitial pneumonia
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Answer: A. Alveolar proteinosis.
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The chest radiograph indicates bilateral airspace disease (note
air bronchograms in the lower zones) with a central distribution and
sparing of the lung adjacent to the hemidiaphragms. The high-resolution
CT scan indicates diffuse ground-glass densities with thickened
intralobular and interlobular septa, producing polygonal shapes. This
has been referred to as "crazy paving." Although a characteristic
finding in alveolar proteinosis, it can also occur in
Pneumocystis carinii pneumonia and sarcoidosis.
The other choices have different radiographic appearances. In
lymphangitic carcinomatosis, the chest radiograph shows a
reticulonodular pattern, with predilection for the lung bases and
Kerley-B lines. The CT scan (Fig 3)
typically will show a polygonal appearance of these lines (arrowhead),
but they are at the lung periphery and extend to the pleural
surfaces.
Mixed alveolar interstitial infiltrates appear in
hypersensitivity pneumonitis. However, the CT scan, in addition to
demonstrating ground-glass densities (nonspecific interstitial
pneumonia), also shows soft centrilobular nodules due to the
bronchiolocentric character of the granulomas (Fig 4)
.
Bronchiolitis obliterans organizing pneumonia is characterized by
patchy airspace consolidation on both chest radiograph and CT scan (Fig 5)
.
Desquamative interstitial pneumonia can present with an identical chest
radiograph; however, the CT scan will indicate ground-glass densities
without polygonal lines (Fig 6) .
Moreover, desquamative interstitial pneumonia, in the
majority of cases, is found in current smokers.
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Figure 6.. High-resolution CT of
desquamative interstitial pneumonia demonstrating diffuse nonspecific
ground-glass density. A similar appearance is found with nonspecific
interstitial pneumonia and respiratory bronchiolitis-associated
interstitial lung disease.
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Suggested Readings
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Hallman M, Merritt TA. Lack of GM-CSF as a cause of pulmonary
alveolar proteinosis. J Clin Invest 1996; 97:649–655
Lee KN, Levin DL, Webb WR, et al. Pulmonary alveolar proteinosis: high
resolution CT, chest radiograph, and functional correlations. Chest
1997; 111:989–995
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Introduction
Answer: A. Alveolar proteinosis....
