Findings: the PA radiograph shows an ill-defined opacity in the right mid-lung field (A, white arrows) which looks intrapulmonary. There is blunting of the right costophrenic angle, indicative of pleural disease (A, red arrow).

The main diagnostic findings are seen in the lateral view. There are oblique posterior pulmonary strands (“crow’s feet”) (B, white arrow) which lead our attention to a posterior vertical white line (B, red arrows), which represents calcified pleura.
A negative finding is the absence of pulmonary disease in the lateral view.

These findings are better seen in the cone down views (C and D, arrows) .

Analysis of findings:
1. Apparent pulmonary disease in the PA radiograph
2. No visible pulmonary disease in the lateral view
3. Blunting of costophrenic angle with calcified posterior pleura
4. Crow’s feet

Summing up the findings: The apparent pulmonary disease in the PA view, which was not seen in the lateral view, together with chronic pleural disease (evidenced by blunting of the costophrenic angle and calcified posterior pleura) are highly suggestive of pleural disease simulating a pulmonary infiltrate.

APPARENT PULMONARY DISEASE IN THE PA RADIOGRAPH, NOT SEEN IN THE LATERAL VIEW + CALCIFIED PLEURA IN THE LATERAL VIEW = CALCIFIED PLEURA SIMULATING PULMONARY DISEASE.

Enhanced axial CT confirms the posterior calcified pleura (A, arrow), the lack of pulmonary infiltrate, and the crow’s feet adjacent to the diseased pleura (B, red arrow).
Crow’s feet are better seen in the coronal and sagittal reconstructions (C and D, red arrows), especially the sagittal view, which is practically identical to the lateral chest radiograph.

Final diagnosis: Pleural calcification simulating pulmonary infiltrate

(My heartfelt thanks to Dr. Eva Castañer for providing the CT images)

Pleural calcifications are not uncommon. Bilateral calcifications are almost always related to asbestos exposure. Unilateral calcifications are usually due to a previous infection or hemorrhage. In any case, when located in the anterior or posterior chest wall they are seen en face in the PA radiograph and may be confused with pulmonary infiltrates, as in the present case. Seen in profile in the lateral view they appear as a calcified line, and the diagnosis is then evident.

Sometimes, the calcified pleura are overlooked. In this particular case we have a useful marker that points our attention to the diseased pleura: the radiologic sign known as crow’s feet which represents subsegmental areas of peripheral fibrosis/atelectasis fixed by the fibrotic pleura. They are likely an early stage of rounded atelectasis. (Personally, I prefer the alternative term sun rays rather than crow’s feet. As a frequent visitor to Minorca, I am more familiar with sun rays than with crows, let alone their feet).

To emphasize the deceitful appearance of pleural calcification, I am showing two more cases.

FIRST CASE

Radiographs belong to a 52-year-old asymptomatic woman. The PA radiograph shows what appears to be a poorly-defined pulmonary infiltrate in the left lung (A, arrow). The lateral view shows two calcified pleural plaques: the posterior one is depicted as a calcified line (B, white arrow), whereas the anterior one is more oblique and simulates a rounded opacity (B, red arrow).

Sagittal CT clearly shows the anterior (C, arrow) and posterior plaques (D, arrow). No pulmonary infiltrates were seen in the lung view (not shown).

SECOND CASE

Preoperative PA chest radiograph in a 57-year-old man. There are several opacities in the left hemithorax that may be pulmonary infiltrates (A, white arrows) accompanied by left diaphragmatic and pleural calcifications (A, red arrows).

In the coronal CT (B) there are no lung abnormalities. Enhanced axial and sagittal CTs depict extensive pleural calcification (C and D, arrows). The apparent pulmonary infiltrates were due to pleural calcifications depicted en face. The patient had a history of TB in his youth.

Dr. Pepe’s teaching points:

1. Pleural disease can simulate pulmonary infiltrates.

2. Crow’s feet can direct our attention to overlooked pleural disease