Esophageal tumors are classified as either benign (noncancerous) or malignant (cancerous). Malignant tumors are aggressive and prone to spreading throughout the body (spread to other areas of the body). The vast majority of esophageal tumors are malignant.
Esophageal tumors are extremely rare in dogs and cats. The most common types of esophageal tumors include leiomyosarcomas (dogs), fibrosarcomas, osteosarcomas, and undifferentiated sarcomas, all of which are malignant. Benign tumors can also occur and include leiomyomas (the most common) and plasmacytomas. Esophageal tumors are mostly found in the lower esophagus in dogs.