Dr. Pepe’s Diploma Casebook: CASE 144 – SOLVED

Dr. Pepe

7 years ago

Dear Friends,
presenting chest radiograph of a 77-year-old man with malaise and weight loss.
What do you see?

This is the last case before the summer. Will see you again in September. Enjoy your vacation!

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Findings: PA radiograph shows increased opacity of the left hilum (A, arrow), which is due to a mass projected over it, as seen in the lateral view (B, arrows). In addition, there is convexity of the aortopulmonary window (A, red arrow)

The increased hilar opacity (C, arrow) was not visible in a PA radiograph taken six months earlier (D, circle). Convexity of the aortopulmonary window (C, red arrow) was not present at that time.

In the lateral view, the mass (E, arrows) was visible six month earlier, albeit smaller (F, arrow). This progression indicates rapid growth.

Enhanced axial and coronal CT confirms a pulmonary mass invading the aortopulmonary window (G and H, arrows). Lung metastases were present (insert, red arrows)

Diagnosis: lung carcinoma invading the aortopulmonary window

I am presenting this case to discuss the aortopulmonary window (APW), which is a small mediastinal space located between the aortic knob and the pulmonary artery in the PA view (Fig 1A). The APW is normally concave; convexity (Fig 1B) suggests an abnormality that should be studied with enhanced CT.

Visibility of the APW is difficult in the elderly, because the superimposed uncoiled descending aorta makes the interpretation more difficult (Fig 2).

*Fig 2. 67-year-old man with moderate dyspnea. A calcified lymph node (A-D, red arrows) marks the APW, which is hidden in the PA view by the elongated descending aorta.*

Convexity of the APW may be overlooked unless we look specifically at the area (fig 3). The larger the abnormality, the more readily it is detected in the chest radiograph. Subtle changes are more difficult to identify and comparing with previous films is very helpful.

Fig. 3. 55-year-old man consulting for acute chest pain. PA film shows two Hampton humps in the right lower lung (A, white arrows). The left hilum is abnormal (A, red arrow). Enhanced coronal CT confirms the infarcts (B, white arrows), as well as a pulmonary mass (B, red arrow) and lymphadenopathy in the APW (B, yellow arrow). Findings were overlooked in a radiograph taken seven months earlier (C, yellow and red arrows). Proven bronchogenic carcinoma.

Causes that may alter the APW are: tumors, enlarged lymph nodes, aortic aneurysms and increased mediastinal fat. The phrenic nerve crosses this space and a phrenic neurinoma may also grow in the APW, although I have never seen a case.

Enlarged lymph nodes are by far the most common cause of occupation of the APW. They may occur in malignant and non-malignant diseases. They usually coexist with radiographic manifestations of the primary process (Figs 4 and 5).

*Fig 4. 59-year-old man with apical LUL carcinoma (A and B, arrows). There is a marked bulge of the APW (A and B, red arrows). Moderate pneumothorax after needle biopsy.*

*Coronal and axial CT confirm metastatic lymph nodes in the APW (C and D, red arrows)*

Fig 5. 33-year-old woman with low-grade fever and malaise. Chest radiographs shows a non-descript infiltrate in the anterior segment of the RUL (A and B, arrows). In addition, there is a prominent bulge in the APW, highly suspicious of lymphadenopathy (A, red arrow). Diagnosis: Hodgkin lymphoma.

In isolated occupation of the APW the etiology cannot be determined in the chest radiograph and enhanced CT should be obtained (fig 6).

Fig 6. Routine check-up in a 60-year-old woman. PA radiograph shows moderate convexity of the APW (A, arrow). Enhanced CT confirms enlarged lymph nodes in the APW (B and C, arrows), mediastinum and hila. Diagnosis: sarcoidosis

Aortic aneurysm is an uncommon cause of convexity of the APW (Fig 7). The abnormality is initially subtle and it becomes more evident as the aneurysm grows (Fig 8).

Fig 7. 78-year-old man without significant symptoms. PA radiograph shows a mediastinal mass protruding at the level of the APW (A and C arrows). The mass is also evident in the lateral view (B and D, arrows).

Radiographs taken five years earlier did not show the abnormality (E and F, circles).

Enhanced axial and coronal CT demonstrate that the mass represents a saccular aneurysm arising from the aortic arch (G and H, arrows).

Fig 8. 78-year-old man after a fall. PA radiograph shows numerous rib fractures (A, white arrows). An additional finding is a mediastinal opacity at the APW (A, red arrow), also visible in the lateral view (B, red arrow).

Comparison with previous films shows a normal APW in 2007 and progression of the opacity over a three-year period (arrows).

Enhanced CT shows that the opacity represents a partially thrombosed aneurysm arising from the inferior aspect of the aortic arch (C-D and E, arrows).