Two patients with opacification of the lower portion of one lung.
Despite the similar radiographic appearance of the PA views, the
cause of the opacification is quite different. This is reflected
by the differences in their lateral views.
- Patient 14A. A 32-year-old
woman was hospitalized for an asthma exacerbation. She also had
a history of alcoholism and was intoxicated at the time of her presentation
to the ED (Figure 1).
- See patient outcome.
- Patient 14B. A 32-year-old man
complained of left-sided pleuritic chest pain (Figure 2).
- See patient outcome.
- What is the
explanation of the radiographic findings in these patients?
Patient 14A: What Is the
Differential Diagnosis of Opacification of the Lower Portion of
The first possibility is consolidation due to pneumonia. Although this is consistent
with the patient’s clinical presentation, several radiographic
findings argue against this diagnosis. First, it is unusual for
pneumonia to cause such homogeneous opacification of the lung. With
pneumonia there usually are aerated alveoli and bronchi interspersed within
the infiltrate (air-alveolograms and air bronchograms) that gives
pneumonia a mottled appearance (inhomogeneous opacification).
Second, pneumonia usually has ill-defined margins. An infiltrate
can have a well-defined margin when it is adjacent to an interlobar
fissure. In this patient’s PA view, the upper margin of
the opacity is sharp (Figure 3A). This sharp horizontal margin seems
as though it would represent the minor fissure (horizontal fissure)
as would occur with consolidation of the right middle lobe. However,
on the lateral view, the corresponding horizontal line lies posterior
to the hilum, not anterior as would be expected if it were the minor
fissure (Figure 3B).
PA and lateral views—Patient 14A.
A second possible diagnosis is
a pleural effusion. A pleural effusion
does cause homogeneous opacification, as is seen in this patient.
In addition, on an upright chest radiograph, a pleural effusion
characteristically has a sharp superior margin. However, the effusion’s
upper margin usually curves upward at the lateral chest wall, forming
a meniscus. In this patient, there is
no meniscus. In addition, a right lateral decubitus chest radiograph
(right-side down) was obtained, which did not show layering as would
be expected with a pleural effusion (Figure 4).