Section 1
Look at images 1 and 2.
Image 1
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List 4 abnormal findings in images 1 and 2. What is the predominant distribution of the abnormalities? a)
Peripheral | ||||||||
Image 2
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Section 2
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In the right lung find an example of clustered, small rounded ground-glass nodules. What is their anatomic location? Find an example of consolidation. | ||||||||
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Find and outline three examples of thickened interlobular septa, 2 in the right and 1 in the left lung. Note that some of these enclose a lobule with thickened centrilobular interstitium appearing as a nodule. Find an example of bronchovascular interstitial thickening in the left lung.
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Section 3: Further Definitions of Centrilobular Nodules
Although centrilobular nodules often appear as solid white densities that obscure any vessels, some centrilobular nodules have ground-glass opacity, and sometimes vessels can be seen within them.
Centrilobular ground-glass opacities suggest hypersensitivity pneumonia, atypical infectious pneumonias (pneumocystis, viral, mycoplasmal), pulmonary edema, pulmonary hemorrhage, respiratory bronchiolitis, bronchiolitis obliterans organizing pneumonia, and bronchioloalveolar carcinoma (rare).
While some of the above diseases can have both ground-glass and solid-appearing centrilobular nodules (e.g. hypersensitivity pneumonia, bronchiolitis obliterans organizing pneumonia), many of the diseases characterzed by centrilobular nodules (endobronchial tuberculosis, chronic bronchiolitis, silicosis, Langerhans' cell histiocytosis) do not show ground-glass nodules.
Although ground-glass opacity is common in non-specific interstitial pneumonia, alveolar proteinosis, desquamative interstitial pneumonia, and acute interstitial pneumonia, centrilobular ground-glass nodules are not seen.
Section 4
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Histologic Counterpart of this Ground-Glass Opacity Here, the alveolar spaces are filled with homogeneous, pink material, and the alveolar wall capillaries and small vessels are distended by RBCs. What is the diagnosis? What do the ground-glass centrilobular nodules on the HRCT tell us about the development of this abnormality?
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Differential diagnosis of centrilobular, ground-glass nodules on HRCT: These nodules are commonly seen in hypersensitivity pneumonia, pulmonary edema, and pneumocystis, mycoplasmal, and viral pneumonias. They can also be seen in respiratory bronchiolitis interstitial lung diseae, bronchiolitis obliterans organizing pneumonia, and bronchioloalveolar carcinoma. Note that while the findings of thickened interlobular septa and bronchovascular interstitium are common with lymphangitic tumor, centrilobular ground-glass nodules should not be present. Centrilobular ground-glass nodules, however, may be absent with pulmonary edema, resulting in an appearance similar to lymphangitic tumor.
Histologic differential diagnosis: Filling of alveoli by pink material is seen in exudative pulmonary edema, mucous secretion as in bronchioloalveolar carcinoma, alveolar proteinosis (material not homogeneous), and pneumocystis pneumonia (material foamy). Alveolar transudates usually do not stain pink.
Diagnosis: Pulmonary edema. (The diagnosis of hydrostatic pulmonary edema was confirmed when the abnormalities resolved with diuresis.)
Diagnostic features of hydrostatic pulmonary edema on HRCT
Comment: When thickened interlobular septa are seen at the periphery of the lungs on chest radiographs, they are called Kerley B lines. Their usual cause is pulmonary edema.
1.
a. Thickened interlobular
septa
b. Bronchovascular interstitial
thickening
c. Ground-glass
opacity
d. Consolidation
2. (b) The distribution is perihilar.
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What is their anatomic location? Answer: Centrilobular In the medial lung bilaterally, the ground glass opacities are confluent with some consolidation, whereas more peripherally, they have a centrilobular, nodular appearance. | ||||||||
Clustered ground-glass nodules
Bronchovascular interstitial thickening
1. Pulmonary edema. Note that in this example, the pink staining indicates the presence of some protein. Transudates found in purely hydrostatic pulmonary edema do not have enough protein to stain pink. This picture shows permeability pulmonary edema.
2. The distribution indicates that the edema begins in the centrilobular area, around the terminal bronchiolovascular structures.