Dr. Pepe’s Diploma Casebook: CASE 122 – SOLVED!

Dear Friends,

To finish the chapters in Signs in imaging, I am presenting today radiographs of a 78-year-old man with chest pain.


1. Cardiac tumor
2. Pericardial effusion
3. Cardiomyopathy
4. None of the above

Check the images below, leave your thoughts in the comments section, and come back on Friday for the answer.

Click here for the answer

Findings: PA radiograph (A) shows an apparently enlarged heart. Lateral view shows an anterior band limited by the mediastinal and epicardial fat (B, arrows). This finding, known as the pericardial band sign, is highly suspicious of pericardial effusion.

Cone-down lateral view shows the pericardial band better (C, arrows). In the radiograph three months earlier, the band was present, although thinner (D, arrows). Sagittal CT confirms the pericardial effusion (E, arrows).

Diagnosis: large uremic pericardial effusion simulating cardiomegaly

This week I will conclude the series of signs in chest imaging, presenting signs in the mediastinum. The first is the pericardial band sign.
The normal pericardium is 1-2 mm thick and is rarely seen in the lateral chest radiograph. Pericardial effusion separates the two pericardial layers and is seen as a band outlined by the mediastinal fat anteriorly and the epicardial fat posteriorly (Figs. 1 and 2). Sometimes we only see the epicardial fat displaced posteriorly, a sign that the right ventricle does not reach the anterior wall due to the fluid in the pericardial sac (Fig. 3).

Importance of the sign: It is the most reliable plain film sign of pericardial effusion and is an indication for a confirmatory ultrasound study.

Fig. 1. Typical pericardial effusion, showing the “water bottle” configuration of the cardiac silhouette in the PA radiograph (A, arrows) and a pericardial band in the lateral view (B, arrows). Cone-down view shows the pericardial band better (C, arrows).

The pericardial band sign is especially useful when the appearance of the heart in the PA film is not typical of pericardial effusion (Fig. 2) or when the cardiac silhouette suggests another condition (Fig. 3).

Fig. 2. 57-year-old woman with pericarditis. PA radiograph suggests cardiac enlargement and a prominent central pulmonary artery (A, arrow). Lateral view shows an evident pericardial band (B, arrows), confirmed with CT (C, arrows).

Fig. 3. 64-year-old man with metastasis to the pericardium. PA radiograph shows mediastinal lymphadenopathy (A, red arrow) and a bumpy contour at the left side of the heart (A, white arrows). The lateral view shows a pericardial band outlined at the inner side by the epicardial fat (B, arrow).

Enhanced axial CT shows the pericardial space invaded by metastasis (C, arrow). The sagittal view nicely depicts the pericardial band, outlined posteriorly by epicardial fat (D, arrow).

QUIZ: 48-year-old man with cough.

What is the probability of malignancy?
1. Low
2. 50/50
3. High
4. Can’t tell

Findings: PA radiograph shows increased density of the right hilum (A, arrow), caused by superimposition of a nodule, clearly visible in the lateral view (B, arrow). The lateral view also shows a hilar donut sign (B, red arrows), which is indicative of enlarged lymph nodes. A lung nodule plus lymph nodes suggests a high probability of malignancy.

Enhanced axial CT shows a rounded nodule (C, white arrow) accompanied by subcarinal adenopathy (C, red arrow). PET-CT confirms high uptake of both lesions (D, arrows).

Diagnosis: carcinoma with metastasis to subcarinal lymph nodes

The donut sign is visible only in the lateral view. In a normal lateral chest radiograph, the right and left pulmonary arteries are visualized in front of and behind the trachea and LUL bronchus, simulating a horseshoe (A and B, arrows). The presence of subcarinal lymphadenopathy fills the inferior portion of the ‘‘horseshoe’’, forming a circle and creating a rounded opacity in the shape of a donut (C, arrows).

Importance of this sign: suggests enlarged lymph nodes and is an indication for enhanced CT for confirmation

The donut sign is helpful when hilar enlargement is not clear in the PA view, whereas obvious lympadenopathy is seen in the lateral view (Fig. 5).

Fig. 5. 43-year-old patient with uveitis. In addition to pulmonary infiltrates, there is a paratracheal adenopathy in the PA radiograph (A, arrow). It is difficult to determine whether there is hilar adenopathy. The lateral view clearly shows a donut sign (B, arrows), confirmed with enhanced CT (insert, arrows). Diagnosis: sarcoidosis

The donut sign is very helpful for distinguishing between large hila due to enlarged pulmonary arteries and hilar enlargement secondary to lymphadenopathy (Fig. 6).

Fig. 6. Two patients (A and B) with enlargement of both hila. Personally, I would find it difficult to say whether the features are due to enlarged arteries or lymphadenopathy.

Lateral views show enlarged right and left pulmonary arteries in the first case (C, arrows), secondary to pulmonary arterial hypertension. The second case shows an obvious donut sign (D, arrows), due to enlarged lymph nodes in a patient with lymphoma.

QUIZ: 67-year-old oncologic patient with shortness of breath. What do you see?

Findings: aside from the lung changes, there is a protrusion of the aortic knob (A, red arrow), known as aortic nipple. In addition, there is azygos vein enlargement, visible in the PA and lateral views (A and B, white arrows).

Unenhanced coronal CT shows a large azygos vein (C, arrow) and the aortic nipple at the aortic knob (C, red arrow). Axial CT shows the enlarged azygos (D, white arrow) and the left superior intercostal vein circling the aortic knob (aortic nipple) (D, red arrow).
Axial CT of the abdomen depicts a collapsed IVC with calcium inside (E, arrow).

Diagnosis: thrombosis of IVC with azygos and hemiazygos acting as collateral channels

The term aortic nipple refers to a small protrusion of the contour of the aortic knob, visible in up to 10% of PA radiographs. It is caused by the left superior intercostal vein, which connects with the hemiazygos vein, circling around the aortic arch. Normal size is around 1-2 mm (A and B, arrows). A large nipple suggests increased flow in the left hemiazygos system (C and D, arrows).

Importance of this sign: An enlarged aortic nipple indicates increased flow in the azygos/hemiazygos system, related to impaired circulation of the inferior or superior vena cava. This may occur in congenital interruption of the SVC or IVC, or be secondary to acquired thrombosis. These options should be investigated with enhanced CT.

Usually, the azygos vein carries more flow than the hemiazygos. Lack of enlargement of the azygos in the PA view accompanied by a large aortic nipple suggests congenital absence of the azygos vein (Fig. 7).

Fig. 7. Asymptomatic 45-year-old man with a large aortic nipple (A, arrow). Note that the azygos vein is not seen (A, asterisk). Enhanced CT shows a large hemiazygos (B and C, arrows). An axial slice shows a large left superior intercostal vein (D, arrow). The azygos arch is missing (D, asterisk). Diagnosis: congenital interruption of IVC with hemiazygos continuation and azygos vein agenesis

Occasionally, a small aneurysm of the aortic knob may simulate an aortic nipple. The correct diagnosis should be established with enhanced CT (Fig. 8).

Fig. 8. Asymptomatic 67-year-old man with a small aortic aneurysm erroneously diagnosed as aortic nipple ( A, arrow). The diagnosis should be challenged because the aneurysm is visible in the lateral view (B, arrow). The aneurysm is confirmed in a previous CT (C, arrow) taken for RUL pneumonia.

Follow Dr. Pepe’s advice:

1. The pericardial band sign is highly reliable to suspect pericardial effusion in the lateral chest radiograph.

2. The donut sign is very useful to diagnose mediastinal lymphadenopathy.

3. The nipple sign is a good indicator of impaired flow in the SVC or IVC, either congenital or acquired.

12 thoughts on “Dr. Pepe’s Diploma Casebook: CASE 122 – SOLVED!

  1. There is an enlarged of the cardiac shadow on AP view, may have nany DDx, as mentioned above, but in Lateral view there is a sign called oreo cookie sign, reflecting dusplacement of epicardial fat from pericardial fat, representing Pericardial effusion.

  2. Good morning! Pericardial effusion. On lateral x-ray the pericardium is thickened and delimitated by mediastinal fat

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