Paraesophageal Omental Hernia Mimicking Thoracic Aorta Aneurysm

Case History: A 59-year-old man with medical history significant for hypertension who presented with an episode of severe coughing, choking and labored breathing which occurred while talking and laughing, raising the suspicion for aspiration. Upon presentation to emergency department, he denied any chest pain, shortness of breath, and coughs. Review of systems was otherwise negative.

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FIGURE 1

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FIGURE 2

A chest X-ray was done which did not reveal any evidence of aspiration or foreign body in the major airways (Fig. 2).

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FIGURE 3

However, as an incidental finding in PA view, shadow of the distal descending thoracic aorta was enlarged and measured to be as dilate as 8.2 cm. Lateral view could not define borders of descending aorta in the lower third segment (Fig. 3).

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FIGURE 4

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FIGURE 5

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FIGURE 6

The patient denied any history of aortic aneurysm. However, as the patient had history of hypertension and chronic smoking, further evaluation to rule out aortic aneurysm was considered and discussed with the patient. After getting a written consent, chest CT angiography was done and showed intrathoracic fat mass adjacent to the distal segment of the intrathoracic esophagus is in direct continuity with the subdiaphragmatic omental fat, confirming the diagnosis of paraesophagial omental hiatal hernia (Fig 4-6).

Diagnosis: Paraesophagial omental hiatal hernia, mimicking descending thoracic aorta aneurysm

Discussion: Intrathoracic omental herniation through the esophageal hiatus is extremely rare and often asymptomatic. Most of the cases are found incidentally and misdiagnosed as mediastinal lipoma after being identified as an intrathoracic mass. Although most of the patients are asymptomatic, some can present with dysphagea. The underlying mechanism is cephalad migration of phrenoesophageal membrane, which is supposed to be an age related phenomenon.

Paraesophagial omental hiatal hernia is a very rare finding in chest CT and CXR. In our patient the intrathoracic omental mass adjacent to the distal third of descending thoracic aorta mimics a thoracic aorta aneurysm. Chest CT is helpful in the differential diagnosis. If the diagnosis is not clear, Magnetic Resonance Imaging (MRI) is the diagnostic tool of choice and provides the highest diagnostic accuracy by a noninvasive modality. If the signal intensity inside the mass is inhomogeneous, a concern may remain that malignancy is possible. In some cases surgical and pathological confirmation of benignity is required.

Ali Gholamrezanezhad, MD, FEBNM
Radiology resident, Yale New Haven Hospital, Saint Raphael Campus

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