Tumours of the oral cavity Flashcards
Differential diagnoses for oral masses
NEOPLASIA
Gingival hyperplasia - boxer dogs!
Eosinophilic granuloma - cats
Craniomandibular osteopathy - WHWT
What do suspect if oral mass in boxer dog?
Gingival hyperplasia
What do suspect if oral mass in cats?
Eosinophilic granuloma
What do you suspect if there’s an oral mass in WHWT?
Craniomandibular osteopathy
Epidemiology of oral tumours
The oral cavity is a common site for the development of tumours in small animals, superceded only by the skin and soft tissues, mammary tumours and haematopoeitic tumours.
Malignant oral tumours account for about 6 % of all canine cancers and 3 % of feline cancers.
Oral tumours generally arise in older animals.
Pathology of oral tumours
A broad spectrum of tumour types.
Tumours range from the benign “epulides” to the more aggressive squamous cell carcinoma, fibrosarcoma and the highly malignant melanoma.
Malignant melanoma is more common in small, older dogs. Sarcomas more common in retriever type breeds.
SCC not that breed specific.
Clinical signs of oral tumours
Dysphagia,
Halitosis,
Excessive salivation, purulent / blood stained saliva
Oral haemorrhage,
Displacement or loss of teeth
Facial swelling.
Imaging techniques for oral tumours
Good quality radiographs of the tumour site are important to evaluate the extent.
Lateral and dorso-ventral/ ventro-dorsal views of the skull may be useful but dental, intra-oral films provide better detail.
Ultrasound is not generally very helpful for imaging tumours of the oral cavity but CT and MRI are being used increasingly for evaluation of such tumours for pre-surgical planning.
Bony changes that can occur in association with oral tumours
osteolysis (may be punctate or permeative, or occasionally expansile bony lesions)
irregular periosteal new bone
mineralization of soft tissue tumours.
Biopsy/FNA of oral tumours
Usually anaesthetise for biopsy and radiographs
Cytology is of limited value in the tumour but is important for evaluation of enlarged submandibular lymph nodes.
Most intra-oral neoplasms are accessible for biopsy. However, their surface may be infected or necrotic and hyperplastic or inflammatory reactions in the adjacent tissues are common thus care must be taken to ensure a representative sample.
What type of biopsy should be used for oral tumours
As many oral tumours involve the underlying bone a deep wedge or Jamshidi needle-type biopsy is recommended.
Staging of oral tumours
Primarily by physical examination and radiography.
More than half the tumours occurring at this site are malignant.
The lymphatic drainage of the oral cavity is primarily to the submandibular lymph nodes.
Regional drainage is to the retropharyngeal nodes and via the cervical chain to the prescapular and anterior mediastinal nodes.
The tonsils should also be evaluated especially in the case of malignant melanoma.
Surgery for oral tumours
The most effective means of treatment.
The entire tumour must be excised with adequate margins of surrounding normal tissue.
Since a high proportion of oral tumours involve bone it is essential that the surgical margins are achieved in the bone as well as in the soft oral tissues.
Mandibulectomy and maxillectomy permit wide local excision of oral tumours with 1 - 2 cm margins of resection and have been used successfully in the management of basal cell carcinoma, squamous cell carcinoma and low grade fibrosarcoma.
Radiotherapy for oral tumours
Offers the advantage of treating larger areas of tissue surrounding the tumour than may be possible by surgery and high energy megavoltage radiation has good penetration of bone.
Local lymph nodes can also be included in the treatment fields where necessary.
The main indication for radiotherapy is in the treatment of oral tumours which are not amenable to surgical excision.
Quite successful as a single agent in the management of gingival carcinomas in the dog and for palliation of oral malignant melanoma.
The combination of surgery with post-operative radiotherapy is probably the most effective treatment for oral sarcomas in the dog.
Radiotherapy has been less successful in the management of malignant oral tumours in the cat.
Chemotherapy for oral tumours
Does not play a role in treatment of most oral tumours in the cat or in the dog with the exception of muco-cutaneous forms of lymphoma.
Benign Tumours of the Oral Cavity
The “Epulides”
a group of common, non-metastatic oral tumours arising in association with the gingiva.
represent up to 40% of all oral tumours in the dog, they are relatively uncommon tumours in the cat.
What are the two distinct tumour groups that make up the “Epulides”?
benign fibromatous / ossifying epulis (peripheral odontogenic fibroma)
locally aggressive basal cell carcinoma (BCC) (Acanthomatous ameloblastoma)
Peripheral Odontogenic Fibroma (POF)
The most common oral tumour in the dog
Typically affects middle aged to older dogs of any breed.
Brachycephalic dogs such as boxers may be prone to developing multiple epuli.
These tumours are rare in the cat.
The aetiology is not known.
Presentation of Peripheral Odontogenic Fibroma (POF)
This tumour presents as a firm - hard mass usually with a smooth, non-ulcerated surface.
It is firmly attached to the gingiva and periosteum of the dental arcade and grows outward, often from a relatively narrow base.
Pathology of Peripheral Odontogenic Fibroma (POF)
Tumours show varying degrees of mineralisation, leading to the arbitary distinction between the fibromatous and ossifying forms.
The term peripheral odontogenic fibroma has been proposed to encompass both types on the basis that although they contain elements of odontogenic epithelium, they appear to be of mesenchymal origin.
Behaviour of Peripheral Odontogenic Fibroma (POF)
Clinically these tumours are benign, they never invade into the adjacent bone and never metastasise.
Treatment of Peripheral Odontogenic Fibroma (POF)
The treatment of choice is local surgical excision.
Resection of alveolar bone at the base of the mass may be necessary to effect a complete removal but the prognosis is excellent.
Acanthomatous epulis / ameloblastoma, Basal Cell Carcinoma (BCC)
Tumours occur principally in middle-aged dogs, although are occasionally reported in younger animals.
Medium to large breeds tend to be affected, there might be a male predilection.
The aetiology is not known.
Presentation of Acanthomatous epulis / ameloblastoma, Basal Cell Carcinoma (BCC)
The gross appearance of this tumour is variable, it may present as an irregular, fungating epithelial mass or may be more invasive with an ulcerated appearance and occasionally contains areas of necrosis.
Radiographically there is usually lysis of adjacent alveolar bone and displacement or loss of teeth is common.
Occasionally the soft tissue of the tumour becomes mineralised.
Pathology of Acanthomatous epulis / ameloblastoma, Basal Cell Carcinoma (BCC)
The term basal cell carcinoma has been applied to this tumour on the basis that the lesion is predominantly composed of clumps of basal epithelium attached to and apparently originating from the stratum germanitivum of the overlying gum.
The consistent infiltration into bone being characteristic of the behaviour of a carcinoma.
Behaviour of Acanthomatous epulis / ameloblastoma, Basal Cell Carcinoma (BCC)
a locally aggressive tumour and invariably invades the adjacent alveolar bone.
does not metastasise, it does present a clinical problem by virtue of the invasive pattern of growth.
Treatment of Acanthomatous epulis / ameloblastoma, Basal Cell Carcinoma (BCC)
wide local excision including a margin of at least 1 cm of alveolar bone beyond the gross or radiographic limit of the tumour.
radio-sensitive and high cure rates can also be achieved by radiotherapy .
However, surgery is the preferred treatment because there is a risk of the subsequent development of malignant tumours at the site of irradiated tumour
Ameloblastoma
a rare dental tumour which arises from odontogenic epithelium.
Typically it occurs in young animals
In dogs the mandible is the usual site whereas a fibromatous form of ameloblastoma appears to be more frequent in the maxilla of young cats, especially the region of the upper canine.
Presentation of ameloblastoma
At either site the expansive growth of the tumour results in gross swelling and distortion of the bone.
The tumour is composed of well defined, large cystic cavities and thus has a characteristic multiloculate radiographic appearance
Behaviour of ameloblastomas
Benign
Treatment of ameloblastoma
can be cured by complete surgical resection.
There is some evidence that curretage of the bony cavities is sufficient to achieve local control.
Malignant oral tumours
Squamous cell carcinoma
Fibrosarcoma and other sarcomas
(Osteosarcoma)
Malignant melanoma
Squamous Cell Carcinoma (SCC)
the most common malignant oral tumour in the dog and cat.
In the dog it accounts for approximately 20 – 30% of malignant oral tumours and tends to occur in older animals (average 8 - 10 years) of medium to larger breeds.
There is no sex predilection.
In the cat, SCC accounts for 70% of malignant oral tumours, it also occurs in older animals (average age 10 years) with no sex predilection.
Presentation of gingival SCC
may arise at any site in the upper and lower dental arcades.
usually begins at the gingival margin and its invasive growth leads to destruction of the peridontal tissues and loosening of the teeth.
The gross appearance is of an irregular, proliferative or ulcerative epithelial lesion.
often friable and haemorrhagic and secondary bacterial infection is common .
Invasion and lysis of adjacent bone occurs in over 70% of cases
Behaviour of gingival SCC
low rate of metastasis
Tumours sited more caudally in the mouth and particularly those involving the caudal maxilla, tend to be more invasive and carry a worse prognosis.
a much more aggressive neoplasm in the cat and there is often severe, deep invasion of bone at the time of presentation.
Treatment of gingival SCC
In the dog, surgery is the treatment of choice for early stage lesions particularly those affecting rostral areas of the mouth.
Wide local excision by maxillectomy or mandibulectomy as appropriate is frequently curative, and 1 year survival rates are in the order of 84%.
In cats the extent of the tumour often precludes surgery and even those tumours deemed operable carry a poor prognosis.
The outcome following radiotherapy is poor.
Fibrosarcoma incidence
The third most common malignant tumour of the canine oral cavity representing 10 – 20 % of malignant tumours at this site.
Although fibrosarcoma is a common tumour in the cat, its incidence in the oral cavity is low (less than 20% of tumours at this site), sites of predeliction being the soft tissues of the head, trunk and limbs.
Fibrosarcoma signalment
It tends to occur in younger dogs, the mean age of onset is 7.5 years but up to 25% occur in animals under 5 years of age.
There is a 2:1 male:female ratio and the Retriever breeds appear to suffer a particularly high incidence.
Presentation of fibrosarcoma
In the dog it most commonly involves the upper dental arcade often extending dorsally and laterally into the paranasal region and medially onto the palate.
firm, smooth mass with a broad base and in its early stages may be difficult to distinguish on gross inspection from gingival hyperplasia or POF.
Radiographic evidence of bone involvement is common in more advanced tumours but in general fibrosarcoma tends to cause less lysis than SCC or BCC and is more often associated with a proliferative periosteal reaction.
Behaviour of fibrosarcoma
The histological appearance of fibrosarcoma of the oral cavity does not always correlate well with the biological behaviour of the tumour.
Some tumours may appear histologically low grade and yet show a very aggressive and infiltrating behaviour.
Local and distant metastasis occurs in around 25% of cases but the prognosis is always guarded due to the extensive infiltration of adjacent tissues.
Treatment of fibrosarcoma
No single form of treatment has been found to be entirely effective.
Wide local surgical excision by mandibulectomy and maxillectomy may control early stage, low grade tumours but even such aggressive surgery does not achieve the compartmental type of resection which is necessary to erradicate most oral fibrosarcomas and one year survival rates with surgery alone are about 50%.
Not particularly sensitive to radiation and radiotherapy alone does not appear to offer any significant improvement in local tumour control over surgery.
However, the combination of surgery with radiation has been shown to improve the initial tumour response and extend patient survival but local recurrence can still occur.
Undifferentiated sarcomas in the oral cavity
A number of less well differentiated sarcomas including haemangiosarcoma, spindle cell sarcomas and anaplastic sarcomas may also arise in the oral cavity of the dog.
As a group these tumours respresent 10- 20% of canine malignant oral tumours.
Presentation of undifferentiated sarcomas
In gross appearance they may resemble fibrosarcoma but in many cases they are more aggressive tumours and present as a rapidly growing mass which may be friable or haemorrhagic and contain areas of necrosis.
Behaviour of undifferentiated sarcomas
characterised by an infiltrative pattern of growth and are often locally advanced by the time of diagnosis.
A higher proportion of these tumours metastasise, usually via the haematogenous route to the lungs and other internal organs
Treatment of undifferentiated sarcomas
The principles of management are essentially as for fibrosarcoma although the prognosis is often worse due to the rapid growth rate and higher risk of distant metastases.
Small early stage tumours may be surgically resected and, although most soft tissue sarcomas are not very radioresponsive, cytoreductive surgery combined with radiation therapy can be beneficial in the management of the more advanced tumours.
Osteosarcomas in the oral cavity
Mainly locally infiltrative - rate of metastasis low - moderate
Surgical management bast
Not very radiosensitive or chemosensitive
Adjunctive, post-op RT not shown to be of benefit
Melanoma incidence
Malignant melanomas represent about 30 – 40% of malignant tumours of the oral cavity in the dog. Oral melanoma is rare in the cat.
Melanoma signalment
In the dog oral melanomas characteristically develop in older animals, the average age is 9 - 12 years.
There appears to be a sex predilection with male dogs affected four times more frequently than bitches.
Certain breeds of dog, particularly those with pigmented oral mucosa e.g. poodle, pug and cocker spaniel, may be predisposed to this tumour.
Presentation of melanoma
Common sites in order of prevalence are the gums (especially in the region of the molar teeth), the labial mucosa and the hard palate.
rapidly growing friable and haemorrhagic soft tissue mass.
The degree of pigmentation varies considerably.
Secondary bacterial infection and necrosis may be present.
Invasion of the bone is less common in oral melanoma than with SCC and fibrosarcoma
Melanoma behaviour
amongst the most malignant neoplasms encountered in companion animals.
Irrespective of local tumour control, the major problem presented by melanoma is the high incidence of both regional (nodal) and distant metastasis.
Treatment of melanoma (Oral)
Local control can be achieved by wide surgical resection where the site of the tumour is appropriate or by radiotherapy.
respond to hypofractionated radiotherapy with local response rates approaching 70%.
In the absence of an effective method for the prevention or treatment of disseminated melanoma the prognosis for these tumours is poor and survival rates are in the order of 3 - 6 months.
Summary of tuours of the oral cavity
Relatively common in cats and dogs
SCC most common in cats, prognosis usually poor
SCC, sarcoma, and melanoma main DDx in dogs, prognosis depends on site and stage but melanoma is very metastatic
Tumours of the tongue
Tumours of the tongue are not common in either the cat or the dog but squamous cell carcinoma is the most common histological type of tumour at this site in both species.
Presentation of lingual tumours
often painful and interfere with the function of the tongue.
Difficulties in prehension, mastication and drinking
Excessive salivation (often purulent or blood-tinged)
Halitosis.
Lack of grooming in cats
Lingual tumour behaviour
SCC of the tongue is a particularly aggressive neoplasm which is characterised by rapid extension and invasion into the tongue such that the tumour often involves the full thickness of the tongue by the time of presentation.
Lymphatic invasion and metastasis are common.
Treatment of lingual tumours
Surgery is the treatment of choice
Dogs will tolerate partial glossectomy involving up to 50 percent of the tongue quite well
but in the case of lingual SCC the extensive infiltration of the tongue at the time of presentation often precludes surgical resection.
the tongue is very sensitive to radiation toxicity so radiotherapy has not been a successful treatment
There have been some reports of chemotherapeutic treatment of lingual SCC in dogs and cats with drugs such as cisplatin (not cats), mitoxantrone and doxorubicin but chemotherapy has not become established as an effective treatment for such tumours.
Prognosis for lingual SCC
Overall the prognosis for lingual SCC in both dogs and cats is poor.
In dogs where complete surgical resection is possible 1 year survival rates may exceed 50% but such cases are not common and 1 year survival rates are usually less than 25%.
Tonsilar tumours
Squamous cell carcinoma is the most common tumour to affect the tonsil in dogs and cats.
Other tumours which may arise in the tonsil include:
· Lymphoma (usually as part of multicentric lymphoma)
· Metastatic tumours from the oral cavity, especially malignant melanoma.
Tonsillar SCC is less common than the gingival form in the dog and cat
Aetiology of tonsillar SCC
Associations with environmental pollutants have been implied
Signalment of tonsillar SCC
In the dog the average age of onset of the disease is 9 - 10 years and males are affected three times more often than bitches.
SCC of the tonsil is rare in the cat.
Clinical signs of tonsillar
Usually a unilateral lesion
Early cases tonsil is a relatively normal size but has small papillomatous growths
Dysphagia
Difficulty swallowing
Gagging
Hypersalivation
Weight loss
Temporal muscle atrophy
Tonsillar SCC behaviour
Locally aggressive
High rate of metastasis to retropharyngeal and cervical LNs
Haematological dissemination may also occur
Treatment for tonsillar SCC
Results of surgery/radiotherapy/both are usually poor
No effective chemo
Prognosis bad
Craniomandibular osteopathy
an important differential diagnosis for a bony swelling of the mandible but in contrast to osteosarcoma
usually occurs in juveniles, less than 1 year of age,
usually affects both mandibles, although lesions not necessarily bilaterally symmetrical
strongly breed associated and occurs particularly in West Highland White and Cairn Terriers, although it can arise in other breeds e.g. dobermann.
Nasopharyngeal polyp
not true neoplasms but inflammatory lesions originating from the middle ear or eustachian tube in young (usually < 2 year old) cats.
No breed or sex predilection is known.
Polyps may grow into the external ear canal where they can be seen as a pink, fleshy mass but most grow via a pedicle into the pharynx
Clinical signs of nasal polyps
Stridor / stertor / difficulty breathing
Change in voice
Sneezing
Swallowing problems
Rhinitis
Horner’s syndrome (associated with otitis media)
Diagnosis of nasal polyps
May be seen as soft tissue masses on radiographs of the pharynx or visualised by retraction of the soft palate
Treatment of nasopharyngeal polyps
Most nasopharyngeal polys can be removed by traction.
If an underlying cause can be identified (eg Middle ear disease) then this should be treated appropriately to prevent recurrence.
Osteosarcoma of the skull
less common than that of the long bones in dogs.
There are two distinct variants of osteosarcoma which affect the bones of the canine skull
· Multilobular osteoma/ chondroma / Osteochondrosarcoma / Chondroma rodens
· Mandibular osteosarcoma.
Multilobular osteochondrosarcoma
uncommon tumour which primarily occurs in older, medium to large breed dogs.
relatively slowly growing tumour
usually affects the bones of the calvarium.
Signs and diagnosis of multilobular osteochondrosarcoma
Enlarging mass which is hard and fixed
Characteristic radiographic appearance of dense bony mass of nodular or stippled density
Behaviour of multilobular osteochondrosarcoma
locally invasive and may cause lysis of underlying bone
Treatment of multilobular osteochondrosarcoma
Surgical resection is the only effective treatment but complete surgical removal of the tumour may be difficult or impossible.
Mandibular osteosarcoma
May arise in the ramus of the mandible
one of the five most common tumours of the mandible of dog
Treatment of mandibular osteosarcoma
often possible to control primary tumour by hemimandibulectomy
- usually compartmental resection
Rapid metastasis is not a feature of tumours at this site
