Page 38 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

Chapter 3 · Surgery of the oral cavity and oropharynx

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ight ma illary malignant melanoma in a dog. ote the
3.3 e tension of tumour tissue into alveolar and buccal mucosa.
eripheral odontogenic fibroma of the mandibular incisor
3.2 area in a dog.

• Acanthomatous ameloblastoma has characteristics of
malignancy, including local invasiveness and bone
destruction. However, it does not metastasize and is
therefore considered to be benign (Gardner, 1995).
• Odontomas are not true tumours but rather a
conglomerate of disorganized normal tissue cells. The
mass may be composed of enamel, dentin, cementum
and small tooth-like structures. Lesions with
characteristics resembling normal teeth are considered
to be compound, whereas complex odontomas have a
more disorganized arrangement.
• Less common odontogenic tumours include amyloid-
producing odontogenic tumours and feline inductive
odontogenic tumours.

Other tumours 3.4 uamous cell carcinoma of the right ma illary area in a dog.
Other benign tumours include plasmacytomas, giant cell
granulomas, osteomas and lipomas. and submucosa and frequently invades muscle and bone.
Metastasis to regional lymph nodes is common, whilst
visceral meta stasis to the lungs may occur late in the
Malignant neoplasms disease process.
Malignant melanoma
Fibrosarcoma
These tumours grow rapidly and are characterized by early
invasion of gingiva and bone. Metastasis to regional lymph These occur in similar locations to SCCs, with a greater
nodes occurs early in the disease process. The lung is the frequency along the maxillary dental arch between the
most common site for visceral metastasis. Malignant mela- canine and fourth premolar teeth and on the hard palate.
nomas (Figure 3.3) are dome-shaped or sessile, with vary- The neoplasm is firm and smooth, with nodules that may
ing amounts of pigmentation ranging from black and brown become ulcerated (Figure 3.5). Fibrosarcomas are inva-
through mottled to non-pigmented. Although a minority of sive, and recurrence following local excision is common.
oral melanocytic lesions may be benign, all suspected Early regional lymphatic and visceral metastasis is un-
melanomas should be considered malignant pending usual. Some fibrosarcomas appear benign on histological
microscopic evaluation. Melanomas of the mucocutaneous examination but show malignant behaviour clinically and
junction are invariably malignant. on diagnostic imaging (i.e. histologically ‘low-grade’ but
biologically ‘high-grade’) and thus require similar treatment
Squamous cell carcinoma to other fibrosarcomas (Ciekot et al., 1994).
SCCs may project from oral soft tissues but more com- Other tumours
monly present as ulcerated lesions, frequently involving
the gingiva in dogs (Figure 3.4) and the sublingual tissue Other malignant neoplasms include malignant peripheral
and root of the tongue in cats (Soltero-Rivera et al., 2014). nerve sheath tumours, osteosarcomas, multilobular tumours
Other sites include buccal and labial mucosa, tonsillar of bone, mast cell tumours, lymphosarcomas and undiffer-
crypts and the body of the tongue. SCC destroys mucosa entiated tumours.

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