Page 124 - Atlas of Small Animal CT and MRI

114 Atlas of Small Animal CT and MRI

with central fluid intensity or attenuation and circum- mandible (Figure 1.9.13). Ameloblastic fibro‐odontoma
ferential contrast enhancement. Oral infection can is similar to ameloblastic fibroma with the addition of
spread to other neighboring tissues of the head, such as enamel and dentin. Feline inductive odontogenic tumor
the pharynx and brain (Figure 1.9.8). is unique to cats and is rare, with no imaging features
described. 12
Odontogenic neoplasia Complex odontoma is comprised of dental tissue
that does not form recognizable tooth‐like structures
Odontogenic neoplasia is challenging to classify, and (Figure 1.9.14). These masses are disorganized and
recent reports indicate that further study is required to highly attenuating with expansion of the surrounding
accurately diagnose these tumors. There are several bone. Compound odontoma is a malformation of dental
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categories that can be used to group the dental tumors, tissues that are not organized into a normal tooth
based on the WHO classification scheme. 7,8
structure.
Cysts
Dentigerous cysts are rare and form from squamous Oral cavity neoplasia
epithelium surrounding tooth remnants (Figure 1.9.2). The most common types of neoplasia encountered in
Radicular cysts are lined with squamous epithelium the oral cavity are squamous cell carcinoma, melanoma,
and occur adjacent to the tooth root (Figure 1.9.9). and fibrosarcoma. More rarely encountered tumors,
These lesions cause expansile bone destruction such as liposarcoma, may arise as a soft‐tissue attenuat-
surrounding the tooth of origin and an associated fluid‐ ing mass in the fatty tissues of the tongue (Figure 1.9.15)
attenuating mass. with intense contrast enhancement.
Squamous cell carcinoma is an aggressive tumor
Tumors of the periodontal ligament affecting cats and dogs. In cats, it may cause a mass effect
Fibromatous epulis is a common lesion of soft‐tissue in the soft palate, sublingual or lingual region, lip, buccal
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proliferation in the oral cavity, some of which undergo mucosa, maxilla, or mandible. When adjacent to bone,
mineralization (Figure 1.9.10). Fibromatous epulides and squamous cell carcinoma frequently results in osteolysis,
ossifying fibromatous epulides are subdivided histologically with a primarily lytic appearance and peripheral
into focal fibrous hyperplasia, which is inflammatory and expansion of mineralized tissue with heterogeneous
benign, and peripheral odontogenic fibroma, having contrast enhancement (Figure 1.9.16). When the soft
dental epithelium and a neoplastic behavior. CT imaging palate is thickened in cats, adjacent otitis media or bulla
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features of these lesions have not been described. effusion may occur concurrently (Figure 1.9.17).
Metastasis to the mandibular and retropharyngeal
Tumors of odontogenic epithelium without lymph nodes is common and results in lymph node
odontogenic mesenchyme enlargement with heterogeneous enhancement or well‐
Canine acanthomatous ameloblastoma (acanthomatous defined parenchymal filling defects.
epulis) is an aggressive tumor that can affect the Oral melanoma may also affect the soft tissues of
underlying bone of the maxilla or mandible. This lesion the mouth and can cause osteolysis of adjacent bone.
occurs mainly in medium to large‐breed dogs of middle The soft tissue portion of the mass is expansile and
age, most frequently in the rostral mandible. The major- heterogeneously contrast enhancing (Figures 1.9.18,
ity of dogs had osteolysis of the apical border of the 1.9.19). Metastasis to local lymph nodes is also com-
alveolus with an expansile pattern (Figure 1.9.11). The mon, causing enlargement and peripheral contrast
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soft‐tissue component of the mass shows intense, uni- enhancement with central nonenhancing regions
form contrast enhancement. Amyloid‐producing odon- (Figure 1.9.20).
togenic tumors are benign, mineralizing masses without Fibrosarcoma is the third most common oral tumor
encapsulation and are relatively rare (Figure 1.9.12). in dogs and is generally locally destructive with osteolytic
lesions (Figure 1.9.21). CT scanning can improve
Tumors of odontogenic epithelium with outcomes by defining the tumor margins for surgical
odontogenic mesenchyme planning. 15
Ameloblastic fibroma is a rare tumor that has a benign Primary bone tumors, including osteosarcoma,
behavior and does not recur after excision. Imaging also occur in the oral cavity. They form destructive and
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characteristics of a single case include an expansile productive lesions centered on the bone of origin and
soft‐tissue mass with expansion of the surrounding expand peripherally (Figure 1.9.22).

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