Dr. Pepe’s Diploma Casebook 166 – Big little findings – SOLVED

Findings: the most important feature is a negative finding: absence of air in the gastric fornix (A, circle). Although this is sometimes seen in healthy persons, it is more frequent in distal esophageal obstruction. A careful look discovers that the left mediastinum has a double contour, actually the left wall of the dilated esophagus (A, blue arrow) and the descending aorta (A, red arrow). There is bulging of the right paraesophageal line (A, yellow arrow). A dilated air-filled upper esophagus is visible in the lateral view (B, arrows).

The findings are typical of lower esophageal obstruction with dilatation of the esophagus. The double contour of the left mediastinum is better seen in the cone down view (C, arrows) and confirmed with CT (D, arrows).

The air-filled dilated esophagus in the lateral view (E, arrows) is confirmed with sagittal CT (F, arrows) (T= trachea).

Final diagnosis: unsuspected esophageal achalasia

To my eternal shame, I confess that when I read the initial radiographs I overlooked the findings (nobody’s perfect!). Achalasia was discovered in a routine follow-up CT taken one year later. I redeemed myself in a subsequent pre-op PA radiograph of the patient, in which I saw a double contour of the descending aorta (A and B, red and blue arrows) and bulging of the paraesophageal line (A and B, yellow arrows). I missed the absent air in the gastric fornix, again!

Esophageal achalasia is not an uncommon condition, and early stages can be suspected in the chest radiograph if we pay attention to the telltale signs. Note that these signs are not specific for achalasia and can be secondary to any obstructive process of the distal esophagus. The most revealing findings are:

Absent gastric bubble
Displaced lower mediastinal lines
Air-fluid level in the mediastinum

ABSENT GASTRIC BUBBLE

Occurs in about 10% of the normal population and 50% of achalasia patients, and is due to failure of swallowed air to cross the distal esophageal sphincter. It is a negative finding and therefore, difficult to recognize. When it is detected, we should examine the lower mediastinum, looking for signs of esophageal dilatation (Fig. 1).

DISPLACED LOWER MEDIASTINAL LINES

A dilated esophagus displaces the paraesophageal line toward the right, making it convex. The left wall of the esophagus moves outward, and is sometimes seen as a double contour with the descending aorta (Figs. 2 and 3). Convexity of the paraesophageal line is the most reliable sign and the easiest to detect.

AIR-FLUID LEVEL IN MEDIASTINUM

Excluding hiatal hernia, an air-fluid level in the mediastinum is usually located in the esophagus. It is seen as a straight horizontal line in the middle/upper mediastinum. It is usually related to esophageal obstruction of any cause, the most common being achalasia. Discovery of an air-fluid level should lead us to investigate other signs of esophageal dilatation (Figs. 4 and 5).

Aspiration pneumonia is a complication of achalasia. I’m showing two cases in which the signs mentioned helped to suggest the correct diagnosis (Figs. 6 and 7).

CASE 1.

55-year-old man with pancreatic carcinoma and known achalasia who presented with marked cough. Chest radiographs show bilateral airspace infiltrates. In the PA view there is also dilatation of the upper esophagus (A, white arrows) with an air-fluid level (A, red arrow). The lateral view shows a retrocardiac mass (B, white arrow), suggestive of a dilated lower esophagus. The trachea is displaced forward (B, red arrow). These signs were overlooked by the radiologist, whose diagnosis was widespread pneumonia.

Coronal CT demonstrates widespread air-space disease. It also shows a dilated esophagus (C, arrow). Axial CT images confirm dilatation of the esophagus, which is full of residue
(D and E, arrows).
Final diagnosis: esophageal achalasia with secondary aspiration pneumonia.

CASE 2.

This an old case of a 27-year-old woman with a chronic RUL opacity suspected to be TB (disregard the opacities in both middle lung fields, caused by superimposed breast implants).
PA chest radiograph shows an opacity in the right upper lobe (A, circle). A right paramediastinal line extends from top to bottom (A, arrows). The lateral view shows anterior displacement of the trachea by a tubular structure (B, arrows), which occupies the upper and middle mediastinum. Both findings suggest a dilated esophagus.
Barium swallow confirms the dilated esophagus, secondary to narrowing at the esophagogastric junction (insert, arrow). Considering the age of the patient, achalasia with aspiration pneumonia was the most likely diagnosis, confirmed later.
(Remember that aspiration pneumonia goes to the right upper lobe when the patient is recumbent at night).

Follow Dr. Pepe’s advice:

Subtle findings of distal esophageal obstruction (achalasia) that should not be overlooked:

1. Absent gastric bubble

2. Displaced lower mediastinal lines

3. Air-fluid level in mediastinum