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Oesophageal neoplasia is very rare, accounting for less than 0.5% of all neoplasia in dogs.  It has a higher incidence in the areas where ''Spirocerca lupi'', a [[Helminth|helminth parasite]], is endemic in Africa and the south-eastern USA. The most commonly reported forms of neoplasm are:

 

*'''Squamous cell carcinoma''' - usually apparent as an annualar thickening in the middle third of the oesophagus, anterior to the heart base.

Oesophageal neoplasia is very rare accounting for less than 0.5% of all cancer, except where ''Spirocerca lupi'' is endemic (Africa and South-eastern USA). The most frequently reported types of neoplasm are:

*'''Leiomyosarcoma'''

* Squamous cell carcinoma - usually appears as an annualar thickening in the middle third of the oesophagus, anterior to the heart.

*'''Fibrosarcoma'''

* Leiomyosarcoma

*'''Osteosarcoma'''

* Fibrosarcoma

*'''Plasmacytoma'''        

* Osteosarcoma

*Local invasion of paraoesophageal tumours is much more common than primary oesophageal neoplasia. The most common metastatic tumours are '''thyroid carcinomas'''.

* (Plasmacytoma)        

*Benign '''leiomyomas''' may occur in the caudal oesophagus and gastric cardia.

* (Local invasion of paraoesophageal tumours e.g. thryoid)

* (Leiomyoma - benign, most frequently in the caudal oesophagus and cardia)

* Most are older in age

It may difficult to image the mass by '''ultrasonography''' but this technique may be useful if the mass lies in the cranial mediastinum or close to the diaphragm.

==Description==

====Advanced Imaging Techniques====

In Africa and South-eastern USA the parasitic worm ''Spirocerca lupi'' can cause oesophageal fibrosarcomas and osteoasarcomas. This is most likely due to the parasite secreting a carcinogen. The aetiology of carcinomas in other areas is idiopathic though potentially ingestion of carcinogens may be involved.

'''Computed tomography''' (CT) and '''Magnetic resonance imaging''' (MRI) may be useful in defining the full extent of the lesion and for determining its exact relationship with the oesophagus.

==Diagnosis==

===Biopsy===

===History and Clinical Signs===

If the mass lies in the cranial mediastinum, samples could be obtaind by ultrasound-guided fine needle aspiration (as for a thymoma or thymic lymphoma). Otherwise, excisional biopsies could be obtained by thoracoscopy.

* Non-specific signs of general poor condition and weight loss

* Aspiration pneumonia (secondary to regurgitation)

* Hypertrophic osteopathy as a paraneoplastic syndrome - particulary those with sarcomas with ''Spirocerca lupi'' aetiology

A mass, intra-luminal gas retention or oesophageal stricture with a cranial dilation are not always visible. Contrast studies may be required to define mucosal irregularities and strictures. Swallowing defects and regurgitation can be assessed via fluoroscopy.

===Faecal Analysis===

===Faecal Analysis===

Ova of ''Spirocerca lupi'' can be found in the faeces.

Ova of ''Spirocerca lupi'' may be found in the faeces of affected animals.

==Treatment==

==Treatment==

===Surgery===

===Surgical Management===

Complete tumour excision with oesophageal anastomosis is frequently problematic due to difficulties obtaining complete margins and complications of reconstruction. There can also be complications in the healing of particularly the thoracic oesophagus. One study of 6 dogs who underwent partial oesophagectomy due to Spirocerca-related oeophageal sarcomas reported a median survival of 267 days. 5 of the 6 cases also received doxorubcin. Another study of 4 dogs with oesophageal leiomyosarcoma reported potential long term resolution of clinical signs following marginal surgical resection despite incomplete margins if the tumour was low grade (all were grade 1). Oesophageal bouginage can reduce signs such as regurgitation. Oesophagotomy and gastrostomy tubes can also be used for short term palliation.

Complete tumour excision with oesophageal anastomosis is frequently problematic due to difficulties obtaining complete margins and complications of reconstruction. There can also be complications in the healing of particularly the thoracic oesophagus. One study of 6 dogs who underwent partial oesophagectomy due to Spirocerca-related oeophageal sarcomas reported a median survival of 267 days. 5 of the 6 cases also received doxorubcin. Another study of 4 dogs with oesophageal leiomyosarcoma reported potential long term resolution of clinical signs following marginal surgical resection despite incomplete margins if the tumour was low grade (all were grade 1). Oesophageal bouginage can reduce signs such as regurgitation. Oesophagotomy and gastrostomy tubes can also be used for short term palliation.

===Chemotherapy===

===Chemotherapy===

Rarely reported.

This approach has rarely been reported except as an adjunctive therapy to the surgical removal of ''S. lupi''-associated masses, where '''doxorubicin''' was used post-operatively.

 

===Radiotherpy===

===Radiotherpy===

Limited in the thoracic oesophagus due to poor tolerance of the heart, lungs and other surrounding tissues.  

There is little opportunity to use this technique for oesophageal neoplasia as the surrounding organs (the heart and lungs) have a poor tolerance to radiation.  [[Oesophagitis]] and [[Oesophageal Stricture|oesopageal strictures]] have also been reported after thoracic radiotherapy.  

==Prognosis==

==Prognosis==

Often poor as usually in advanced stages on time of diagnosis therefore limiting resection options. In addition, metastatic rate is high: malignant tumours are locally invasive and metastasis occurs via draining lymph nodes (Cervical and Prescapular lymph nodes in the cervical oesophagus and Mediastinal in the thoracic oesophagus) and haematogenous spread to distant areas.

This is often poor as the disease is usually in its advanced stages at the time of diagnosis, leaving few options for surgical management. In addition, the metastatic rate of oesophageal tumours is high with local invasion and spread to draining lymph nodes (cervical and prescapular nodes from the cervical oesophagus and mediastinal nodes from the thoracic oesophagus) and to distant organs.

==References==

==References==

[[Category:Neoplasia]]

[[Category:Neoplasia]]

[[Category:To_Do_-_James]]

[[Category:To_Do_-_James]]