History
A 6-year-old castrated male Golden Retriever was evaluated because of a 5-day history of regurgitating all solid food within several minutes of eating; the dog was able to retain water and liquid food. The dog had an 11-month history of occasionally vomiting or regurgitating with associated coughing and gagging. The dog's behavior and activity level were otherwise normal. The only abnormality detected on physical examination was mild to moderate dental tartar. The dog had a body condition score of 4 out of 9. Results of a CBC, serum biochemical analysis, and urinalysis were within reference limits. Radiographs of the thorax were obtained (Figure 1).
Lateral (A) and ventrodorsal (B) radiographic views of the thorax of a 6-year-old castrated male Golden Retriever with a 5-day history of regurgitating all solid food within several minutes of eating.
Citation: Journal of the American Veterinary Medical Association 238, 6; 10.2460/javma.238.6.699
Lateral (A) and ventrodorsal (B) radiographic views of the thorax of a 6-year-old castrated male Golden Retriever with a 5-day history of regurgitating all solid food within several minutes of eating.
Citation: Journal of the American Veterinary Medical Association 238, 6; 10.2460/javma.238.6.699
Lateral (A) and ventrodorsal (B) radiographic views of the thorax of a 6-year-old castrated male Golden Retriever with a 5-day history of regurgitating all solid food within several minutes of eating.
Citation: Journal of the American Veterinary Medical Association 238, 6; 10.2460/javma.238.6.699
Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page →
Diagnostic Imaging Findings and Interpretation
A large soft tissue mass measuring approximately 15 × 12 × 13 cm is present in the caudodorsal aspect of the thorax, just right of midline, extending from the tracheal bifurcation to the diaphragm. The structure is causing lateral displacement of the mainstem bronchi and deformation of the adjacent diaphragm. The caudodorsal aspect of the cardiac silhouette appears compressed by the mass (Figure 2). Positive-contrast esophagraphy was performed and revealed that the esophagus was displaced dorsally along the periphery of the mass. The luminal margin of the esophagus appeared normal.
Same radiographic images as in Figure 1 A large soft tissue mass in the caudodorsal aspect of the thorax, just right of midline (white arrows), is evident. Notice the marked lateral displacement of the mainstem bronchi (black dashed arrows). The caudodorsal aspect of the cardiac silhouette appears compressed by the mass (black arrowheads). There is deformation of the diaphragm where it contacts the mass (black arrows).
Citation: Journal of the American Veterinary Medical Association 238, 6; 10.2460/javma.238.6.699
Same radiographic images as in Figure 1 A large soft tissue mass in the caudodorsal aspect of the thorax, just right of midline (white arrows), is evident. Notice the marked lateral displacement of the mainstem bronchi (black dashed arrows). The caudodorsal aspect of the cardiac silhouette appears compressed by the mass (black arrowheads). There is deformation of the diaphragm where it contacts the mass (black arrows).
Citation: Journal of the American Veterinary Medical Association 238, 6; 10.2460/javma.238.6.699
Same radiographic images as in Figure 1 A large soft tissue mass in the caudodorsal aspect of the thorax, just right of midline (white arrows), is evident. Notice the marked lateral displacement of the mainstem bronchi (black dashed arrows). The caudodorsal aspect of the cardiac silhouette appears compressed by the mass (black arrowheads). There is deformation of the diaphragm where it contacts the mass (black arrows).
Citation: Journal of the American Veterinary Medical Association 238, 6; 10.2460/javma.238.6.699
On contrast-enhanced computed tomography (Figure 3), a large rim-enhancing homogenous soft tissue density mass is evident in the caudal mediastinum, beginning in the region of the bronchial bifurcation and extending caudally. The mass is compressing and caudally displacing the diaphragm. Computed tomographic findings were suggestive of a cystic or fluid-filled structure that was causing bronchial and esophageal compression, leading to coughing and regurgitation.
Computed tomographic dorsal (A) and sagittal (B) multiplanar reconstructed images of the thorax of the same dog as in Figure 1. Notice the large homogenous, rim-enhancing soft tissue density mass in the caudal mediastinum (white arrows). The mass begins in the region of the bronchial bifurcation and extends caudally, compressing and caudally displacing the diaphragm (black arrows).
Citation: Journal of the American Veterinary Medical Association 238, 6; 10.2460/javma.238.6.699
Computed tomographic dorsal (A) and sagittal (B) multiplanar reconstructed images of the thorax of the same dog as in Figure 1. Notice the large homogenous, rim-enhancing soft tissue density mass in the caudal mediastinum (white arrows). The mass begins in the region of the bronchial bifurcation and extends caudally, compressing and caudally displacing the diaphragm (black arrows).
Citation: Journal of the American Veterinary Medical Association 238, 6; 10.2460/javma.238.6.699
Computed tomographic dorsal (A) and sagittal (B) multiplanar reconstructed images of the thorax of the same dog as in Figure 1. Notice the large homogenous, rim-enhancing soft tissue density mass in the caudal mediastinum (white arrows). The mass begins in the region of the bronchial bifurcation and extends caudally, compressing and caudally displacing the diaphragm (black arrows).
Citation: Journal of the American Veterinary Medical Association 238, 6; 10.2460/javma.238.6.699
Comments
Surgical exploration of the caudal mediastinum revealed that the mass was a fluid-filled structure with a thick capsule.
The mass did not extend through the diaphragm. Most of the mass was removed. A small portion of the wall of the mass was left in place because of firm fibrous attachments to the esophagus, lung lobes, and diaphragm. Results of cytologic evaluation of the mass fluid were suggestive of serous exudation with evidence of macrophagic inflammation mixed with fresh hemorrhage; no organisms or abnormal cells were seen in the mass fluid. Results of bacterial culture of the mass fluid were negative. Histologic evaluation of the mass revealed diffuse, chronic fibrinous mediastinitispleuritis with moderate pleural thickening caused by granulation tissue, consistent with chronic irritation and inflammation.
In this dog, positive-contrast esophagraphy was useful in ruling out intraluminal esophageal mass or foreign body. Computed tomography is one of the preferred imaging methods for determining the exact location and involvement of a complex intrathoracic lesion.1 Computed tomography revealed that the mass was a fluid-filled structure in the caudal mediastinum. On the basis of the computed tomographic findings, the most likely diagnosis was a mediastinal cyst. Mediastinal cysts are uncommon and most frequently located in the cranial compartment. Cysts should have an epithelial lining, but in this dog, the tissue appeared to be a fibrous capsule of an inflammatory lesion and not a true cyst. The cause of the capsule formation was not histologically apparent, but inflammation of the mediastinum is frequently seen in dogs and cats with esophageal perforation.2 It is possible that the dog had a small esophageal perforation that led to accumulation of a large volume of fluid in the mediastinum, which subsequently caused chronic fibrinous mediastinitis-pleuritis. Esophagraphy failed to reveal evidence of such a perforation or communication of the mass with the esophagus, although a small perforation may have sealed over. Despite aggressive supportive care, the dog underwent cardiopulmonary arrest the second day after surgery and died.
- 1.↑
Prather AB, Berry CR, Thrall DE. Use of radiography in combination with computed tomography for the assessment of non-cardiac thoracic disease in the dog and cat. Vet Radiol Ultrasound 2005; 46:114–121.
- 2.↑
Rousseau A, Prittie J, Broussard JD, et al. Incidence and characterization of esophagitis following esophageal foreign body removal in dogs: 60 cases (1999–2003) J Vet Emerg Crit Care 2007; 17:159–163.
