-Caudal esophageal mural mass with nodules, closely associated with the caudal thoracic aorta

-Partially mineralized cranial mediastinal mass

-Mural mineralization of the aortic arch and descending aorta, associated with the segments of the vessel flanking the cranial mediastinal mass and the caudal esophageal mass –

-Smooth, ventral new bone formation along caudal thoracic vertebra T7-11

-Multifocal mineralization of the liver

Endoscopy was performed immediately following this CT examination, and the esophageal mass was removed. Worms emerged from the lesion upon endoscopic disturbance. Histopathology of the esophageal mass revealed marked nodular lymphoplasmacytic, histiocytic, supprative, and eosinophilic inflammation and intralesional adult nematodes, consistent with a Spirocerca lupi granuloma.

Endoscopic removal was complete. The cranial mediastinal mass was sampled via ultrasound guidance and cytology showed marked macrophagic and neutrophilic inflammation with intralesional parasite ova morphologically consistent with Spirocerca lupi. The patient recovered uneventfully from anesthesia and was lost to further follow-up after treatment with ivermectin and prednisolone.

Spirocerca lupi is a nematode parasite primarily found in tropical and subtropical regions. Dogs are infected by ingesting the intermediate hosts (usually beetles). After ingestion, larvae migrate out of the stomach and into the caudal thoracic aorta via the gastric and celiac arteries. The larvae mature in the wall of the aorta, eventually penetrating through to the adjacent esophageal wall. In the esophagus, the larvae mature to adults and induce the formation of a parasitic granuloma. Neoplastic transformation of these esophageal granulomas is reported, usually into a sarcoma.

Reference:

CT and radiographic characteristics of aortic lesions in 42 dogs with spirocerosis. Kirberger RM, et al.