Dr. Pepe’s Diploma Casebook: CASE 136 – SOLVED

Dear Friends,

Today I am presenting chest radiographs of a 64-year-old man with mild chest pains.

Diagnosis:
1. Elongated aorta
2. Aortic aneurysm
3. Aortic dissection
4. Any of the above

What do you see? Come back on Friday to read the answer!

Click here to see the see the answer

Findings: Chest radiographs show an elongated and probably dilated descending aorta (A and B, arrows). The likely diagnosis lies in a negative finding: the ascending aorta (A and B, asterisk) is not prominent. This is a plain film sign suggestive of type B dissection and indicates an immediate CT.

Enhanced axial and sagittal CT confirm a type B dissection, with enlargement of the descending aorta (C and D, arrows)

Final diagnosis: type B aortic dissection, suspected in the plain film.

I am presenting this case to continue the discussion of negative findings. Diploma 135 was about anatomical structures that were not visible. In today´s presentation I will discuss findings that should be present, but are not.

Discovering missing findings requires a significant degree of knowledge. While noting all the positive findings, we should also consider whether any finding is missing, in the same way that Sherlock Holmes noticed that the dog didn’t bark.

To illustrate this, I will present four cases in which an absent finding in the chest radiograph suggests the correct diagnosis.

CASE 1

71-year-old woman with moderate dyspnea. A right paramediastinal opacity (arrow) was detected in the chest radiograph.

Most likely diagnosis:

1. Mediastinal mass
2. Tortuous innominate artery
3. Goiter
4. Any of the above

Click here to see the see the answer

Findings: The sharp outer border of the opacity suggests a mediastinal mass. The indistinct upper contour (A, arrow) places it in the anterior upper mediastinum. The diagnosis is suggested by a negative finding: the trachea is not pushed towards the left as it should be if the opacity were a goiter or mediastinal mass. Therefore, the most likely diagnosis is a tortuous innominate artery. Enhanced axial CT confirmed this diagnosis (B, arrow).


CASE 2

43-year-old woman with dyspnea and chest pain.
Chest radiographs were read as LUL collapse. Do you agree?

Click here to see the see the answer

Findings: The PA radiograph shows a triangular opacity in the upper left hemithorax that simulates LUL collapse. Again, the diagnosis is based in a negative finding: there is no elevation of the left hilum (A, white arrow), which should accompany collapse. In addition, the trachea is slightly displaced to the right (A, red arrow), suggesting a mediastinal mass. The lateral view (B) is unremarkable.

Click here for the CT

Enhanced axial and coronal CT images show abundant mediastinal fat (C and D, white arrows) occupying the left apex and extending into the neck. The trachea is moderately displaced (C, red arrow).
Final diagnosis: abundant mediastinal fat simulating LUL collapse in the plain film.


CASE 3

Pre-employment chest radiograph in a 43-year-old woman who was told that she had an enlarged ascending aorta.

Diagnosis:

1. Aortic valve disease
2. Marfan disease
3. Aortic coarctation
4. Normal

Click here to see the answer

Findings: the lateral film shows a bulging ascending aorta (B, white arrow). A line has been traced to measure an apparent dilatation of the ascending aorta (B, yellow arrow). The correct diagnosis is based on a negative finding: the ascending aorta should be enlarged in the PA radiograph as well, and it is not (A, asterisk). Therefore, the chest is normal.

The obvious error is that the line is drawn from the anterior aspect of the aorta, outlined by lung air, to an imaginary point in the mediastinum, which may or may not be the posterior aortic wall. Remember that the posterior wall of the aorta is in contact with the mediastinal tissues and, according to the silhouette sign, cannot be visible. Therefore, whoever traced the line was wrong.
MRI confirmed a normal aorta and that no other abnormalities were present. The moderate bulging of the ascending aorta in the lateral film is due to a combination of a moderate pectus excavatum and a narrow AP diameter of the chest (see case below).

Normal chest with an appearance similar to that of the previous case in a 59-year-old asymptomatic man. The narrow AP diameter of the chest accounts for the prominent ascending aorta in the lateral view (B, arrow). The PA radiograph does not show dilatation of the ascending aorta (A, asterisk), confirming the absence of pathology.

Case 4

57-year-old woman with arrhythmia.

How many findings do you see?

1. One
2. Two
3. Three
4. Four

Click here to see the see the answer

Findings: the PA chest radiograph shows four main findings, three of them positive and one negative. The rounded shadow at the aortic knob (A, white arrow) is a typical aortic nipple, secondary to an enlarged left superior intercostal vein (LSIV, red arrow), which joins the brachiocephalic vein superiorly and the hemiazygos vein inferiorly (yellow arrow), giving a double contour to the para-aortic line.
The large aortic nipple indicates increased blood flow in the azygos-hemiazygos system.
The negative finding is that the azygos vein should be enlarged too. However, it is not, suggesting the diagnosis of congenital absence of the azygos vein. Axial enhanced CT confirms the missing azygos vein (B, circle) and the large hemiazygos (B, arrow).

A serendipitous discovery in this case is that the SVC is also absent. Axial CT (C) confirms the lack of SVC (neither right nor left) and the enlarged LSIV (C, arrow). CT reconstructions show the hemiazygos vein (E, red arrows) running parallel to the aorta (A) and draining blood from the innominate veins (D, yellow arrows), which join the LSIV (D, black arrow). Absent SVC is associated with cardiac arrhythmias.



Follow Dr. Pepe’s advice:

1. Discovering negative findings is important in the diagnostic process

2. To do so, evaluate all the visible findings and try to determine whether any that should be there are missing

15 thoughts on “Dr. Pepe’s Diploma Casebook: CASE 136 – SOLVED

  1. To make up for being late last time: aortic dissection – there is calcified atherosclerotic plaque in the middle of lumen. Call referring physician and do CECT. (Also there’s widened and elongated descending aorta with relatively healthy ascending aorta, but it’s the plaque that ensures me).

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  2. Good morning!

    I think there is an elongated and aneurismatic thoracic aorta.
    My eyes can not see disection´s sign… but anything is possible

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  3. Lateral chest view – Descending aorta is prominent and ascending aorta is not – In old age suggestive of AORTIC DISSECTION.
    PA chest view – Widened mediastinum

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  4. Distended and elongated descending aorta and I see a sclerotic plaque in the middle of the aorta lumen (so aortic dissection). CECT for further delineation.

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  5. At this time of the week I can safely say that the correct diagnosis if Type B dissection. More information tomorrow.
    Congratulations to Ner and Genchi Bari, who were the first.

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