GENERAL CONSIDERATIONS

Biologic Behaviour

•esophageal tumors are very rare in both cats and dogs accounting for < 0.5% of all cancers

•female cats are predisposed, but no known breed or sex predisposition in dogs

•malignant tumors are more common and include SCC, leiomyosarcoma, FSA, and OSA

•SCC is common in cats with the middle 3rd of the esophagus cranial to the thoracic inlet most commonly affected

•neuroendocrine carcinoma and adenosquamous carcinoma reported in cats

•sarcomas have been reported secondary to Spirocerca lupi infestation in indigenous areas such as Israel and SE USA

•Spirocerca lupi-induced esophageal sarcomas include FSA, OSA, and undifferentiated sarcomas

•locally invasive with metastasis to regional lymph node via direct extension or lymphatic or hematogenous routes

•benign tumors include leiomyoma and solitary extramedullary plasmacytoma

•solitary extramedullary plasmacytoma have a predilection for the terminal esophagus and cardia

•paraesophageal (i.e., thymic, heart base, or thyroid) tumors can invade the esophagus

•pulmonary and mammary carcinoma can metastasize to the esophagus

•esophageal ADC is possibly associated with cholecystectomy in humans due to bile reflux

CLINICAL FEATURES

Clinical Signs

•clinical signs are non-specific and include debilitation, regurgitation, hematemesis, weight loss, dysphagia, pain during swallowing, and aspiration pneumonia

•regurgitation may be sporadic due to distensibility of esophagus and slowly progressive disease

•hypertrophic osteopathy has been reported especially with Spirocerca lupi­-induced esophageal sarcomas

•Spirocerca lupi-induced esophageal sarcomas are also associated with esophageal granulomas, aortic scarring and mineralization, and spondylitis of the caudal thoracic vertebrae (T6-T12)

•esophageal tumors < 2 cm rarely cause clinical signs

Diagnosis

Survey Radiographs

•survey radiograph findings include:

•gas retention within esophageal lumen

•esophageal dilation proximal to the mass

•soft tissue mass displacing the esophagus or extending into the lumen

•displacement of mediastinal structures

•lumen irregularities

Contrast Esophagram

•contrast esophagram can be performed ± fluoroscopy

•esophagram findings include filling defect, stricture, or intraluminal mass

Esophagoscopy

•esophagoscopy provides direct visualization of the mass and ability to collect biopsy samples

•malignant tumors are usually ulcerated

•leiomyoma appears as circumscribed submucosal mass movable beneath the mucosal layer

•several biopsies should be taken due to prominent inflammation and necrosis, but representative samples are difficult to collect

•iatrogenic perforation is rare with endoscopic biopsy

Other Diagnostic Techniques

•plasma cell tumors may cause hyperproteinemia, hypercalcemia, and monoclonal gammopathy

•fecal flotation test and examination for Spirocerca lupi ova

•open surgical biopsy via either exploratory thoracotomy or cervical exploration

TREATMENT

General Considerations

•treatment is complicated as the majority of cases are advanced at the time of diagnosis

Surgery

•intrathoracic resection is difficult due to poor healing, large resection, anastomotic tension, and poor exposure

•distal esophagus can be reconstructed with gastric advancement through the diaphragm

•esophageal reconstruction has been reported with muscle flaps or microvascular transfer of colon or small intestine

•results of esophageal reconstruction are variable

•en bloc esophageal resection is associated with excellent local control and > 50% long-term survival

•partial esophagectomy with primary esophageal closure has been reported in the management of 6 dogs with Spirocerca lupi-induced esophageal sarcomas with good postoperative recovery and function, and survival times ranging from 2 to > 20 months

    •palliation with enteral nutrition (via E- or G-tubes) or self-expanding intraluminal stent

Radiation Therapy

•indications: tumors of the cervical esophagus

•intrathoracic esophageal tumors should not be irradiated due to poor radiation tolerance of the lungs and heart

Chemotherapy

•unknown

•doramectin (200 µg/kg q 2 weeks SC for 3 treatments) used successfully in dogs with Spirocerca lupi esophageal granulomas

Photodynamic Therapy

•photodynamic therapy using photofrin as a photosensitizer has been described in the management of 1 dog with esophageal SCC with PR and 9-month survival time

Prognosis

•prognosis is poor for malignant esophageal tumors due to difficult surgical resection and high metastatic rate

•prognosis is good for benign lesions following complete resection

•5-year survival rate is < 20% in humans using a combination of surgery, radiation therapy, and chemotherapy