CT-Pathology Correlations

Case 14

Section 1

Look at images 1 and 2.

Image 1

What are the abnormalities?

Answer

Image 2

Section 2

Image 1

Find two parenchymal bands in the right lung.

Find septal lines around a lobule in the right lung.

Image 2

Find a septal line in the right lung.

Find a parenchymal band in the left lung.

Find 2 examples of thickened bronchovascular interstitium in the right lung.

The HRCT images show extensive, bilateral, ground-glass opacity, which is non-uniform, patchy, and varies in density, sometimes in a lobular pattern. This pattern is known as inhomogeneous ground-glass opacity.

Section 3

Image 1

Histologic Findings

Here are portions of 3 lobules showing an early stage of disease with peribronchiolar and alveolar infiltrates that account for ground-glass opacities. The interlobular septa here are edematous, probably accounting for the septal lines of the HRCT.

Find 3 peribronchiolar infiltrates.

Find 2 alveolar infiltrates.

Find the edematous interlobular septa.

The widespread alveolitis probably accounts for the decrease in diffusing capacity seen in this disease.

Image 2

Find an area of peribronchiolar inflammatory thickening.

Find 2 areas of cellular alveolar exudate.

Image 3

Find and name the lesion to the left of the vein (V).

Find this lesion and another like it in image 2.

What type of inflammatory infiltrate is present?

a) Predominantly PMNs
b) Predominantly lymphoid

Answers

Differential diagnosis of ground-glass opacities and interlobular septal lines on HRCT

Acute/subacute presentation: Hypersensitivity pneumonia; pulmonary edema; diffuse alveolar hemorrhage; and viral, pneumocystis, and mycoplasmal pneumonias.
Chronic presentation: Hypersensitivity pneumonia, pulmonary alveolar proteinosis, usual interstitial pneumonia

Histologic differential diagnosis: Hypersensitivity pneumonia, viral pneumonia, bronchiolitis, collagen vascular disease

Diagnosis: Subacute hypersensitivity pneumonia

Diagnostic criteria for subacute hypersensitivity pneumonia by HRCT

Inhomogeneous ground-glass opacity, sometimes respecting lobules (related to air-trapping, which is discussed later in Case 28)
Irregular reticular change, septal lines, and parenchymal bands
Small centrilobular nodules (not illustrated here)

Comment: Hypersensitivity pneumonia usually presents as a subacute or chronic process. Early in the disease, the findings are primarily ground-glass opacities, which may be diffuse or patchy, or there may be ill-defined nodules often with a centrilobular distribution.

See Case Study 18 for another example of hypersensitivity pneumonia.

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