Dr. Pepe’s Diploma Casebook: CASE 131 – SOLVED

Dr. Pepe

7 years ago

Dear Friends,

Today I am showing chest radiographs of a 81-years-old man with chest pain five years after left pneumonectomy for lung carcinoma

Diagnosis:

1. Broncho-pleural fistula
2. Intestinal hernia
3. Empyema
4. None of the above

What do you see?

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 shows an opaque left hemithorax with a central cavity (A, black arrow) with an air-fluid level (A, red arrow). The splenic flexure of the colon is right below (A, yellow arrow). In the lateral view the central cavity has an inverted U-shape (B, black arrows) with two air-fluid levels (B, red arrows).

Unenhanced coronal and sagittal CT show that the central cavity is a dilated stomach (C and D, arrows), herniated through a large rent in the left hemidiaphragm (C and D, red arrows).

Final diagnosis: herniated stomach and colon through a wide diaphragmatic defect

I present this case to increase your awareness of an often forgotten subdiaphragmatic structure: the gastric bubble. Due to its air content, the gastric fornix is visible in most upright PA chest radiographs, and it can provide valuable information.
I have classified changes in the gastric bubble as follows:

1. Absent
2. Malpositioned
3. Displaced
4. Miscellaneous findings

An absent gastric bubble occurs in 10% of the normal population and 50% of patients with achalasia. Therefore, lack of a gastric bubble should prompt a review of the mediastinum to investigate a dilated esophagus (Fig. 1).

Fig. 1. 48-year-old woman with achalasia. Initial film shows a normal mediastinum with a visible gastric bubble (A, arrow). Four years later, the gastric bubble is absent and there is second contour paralleling the aorta (B, arrows), suspicious of a dilated esophagus. Esophagogram confirms the esophageal dilatation and the narrow esophagogastric junction (C, arrow)

Remember that although an absent gastric bubble may suggest a diagnosis of achalasia, visible air in the fornix does not rule it out, as demonstrated in the case below (Fig. 2).

Fig. 2. 57-year-old man with diffuse pneumonia. PA radiographs shows diffuse airspace disease and a redundant, dilated esophagus (A, black arrows). Gastric bubble present (A, red arrow). Coronal CT confirms the dilated, food-filled esophagus (B, arrow). Diagnosis: achalasia with aspiration pneumonia.

An absent air bubble may happen when the stomach is not in the left upper quadrant. This occurs in a rare congenital condition, abdominal heterotaxia, in which there is rotation only of the abdominal structures. In these cases, the gastric bubble is located under the right hemidiaphragm (Fig. 3).

Fig. 3. 51-year-old man with vague chest complaints. PA radiograph shows the gastric bubble on the right side (A, black arrow) and a prominent azygos (A, red arrow). The abdomen shows a left- sided liver (B, black arrow) with the splenic flexure of the colon on the right and the hepatic flexure on the left (B, red arrows). Diagnosis: abdominal heterotaxia

Malpositioned gastric bubble occurs when the fornix is in an abnormal location. The most common cause is diaphragmatic hernia either through the esophageal hiatus (Fig. 4) or secondary to traumatic rupture of the diaphragm (Fig. 5).

Fig. 4. Hiatal hernia with the gastric bubble (A, arrow) above the level of the left hemidiaphragm. Barium confirms herniation of the gastric fornix and narrowing of the stomach where it crosses the hiatus (B, arrow).

Fig. 5. 38-year-old man after car accident and ruptured diaphragm. Note the herniated gastric bubble (A and B, black arrow) and the narrowing where the diaphragmatic tear is crossed (A and B, red arrows). The gastric catheter has stopped at the level of the tear (A and B, yellow arrow).

In left hemithorax opacification, an abnormally located gastric bubble indicates the position of the hemidiaphragm and clarifies the etiology. Downward displacement indicates massive pleural effusion (Fig. 6), whereas elevation favors collapse of the whole lung (Fig. 7).

Fig. 6. Metastatic disease with massive left pleural effusion causing inversion of the left hemidiaphragm. Note the marked descent of the gastric bubble (A and B, arrow), which marks the position of the diaphragm.

Fig. 7. 61-year-old man, short of breath. PA radiograph shows complete left lung collapse, confirmed by elevation of the gastric bubble (A, arrow). CT depicts the collapse and numerous air bubbles within the bronchial tree (B, arrows). Diagnosis: allergic aspergillosis with numerous mucus impactions. Collapse regressed after bronchoscopy.

Gastric bubble displacement is also an indirect sign of an abdominal mass. The most common cause is splenomegaly, which pushes the aerated fornix towards the midline (Figs. 8 and 9).

Fig. 8. 54-year-old man with fever and malaise. PA radiograph shows medial displacement of the gastric bubble (A, arrow) and elevation of the left hemidiaphragm. CT depicts marked splenomegaly with displacement of the stomach and splenic flexure (B, arrows). Lymphoma

Fig. 9. 32-year-old woman after car accident. PA chest film shows uniform opacity of LUQ with elevation of hemidiaphragm and medial displacement of the gastric bubble (A and B, arrows). Angiogram shows a ruptured spleen (C, arrows) and a large lateral hematoma (C, asterisk).

Miscellaneous findings include visualization of masses outlined by air in the gastric bubble and occasionally air within the stomach wall. Masses in the gastric fornix may be due to carcinoma and other tumors, gastric varices, or postoperative deformities (Fig. 10) .

Fig. 10. 45-year-old man after a Nissen procedure. Note the apparent mass outlined by air in the gastric bubble (A, arrow), which looks normal in the preoperative chest radiograph (B, arrow). In the old days, gastric varices were sometimes detected in the chest plain film.

Air in the gastric wall may be seen after ingestion of corrosive substances or, more commonly, after forceful vomiting or secondary to an endoscopic procedure (Fig. 11).