DENTICLES!

Equine Odontogenic TumorsAccessions: 128549, 128572

Jewel 3 yo Belgian Filly Presents for undescribed abnormalities noted

on routine dental exam, no dysphagia PE: palpable asymmetry to the

hemimandibles, mild right mandibular lymphomegaly

Orally, the occlusal surface of 410 is replaced by cobblestone-like surface of multiple "dental islands" with deep periodontal and intradental pocketing

Local feed impaction with fermented odor

Insert CT images

P.M. Dixon, I. Dacre / The Veterinary Journal 169 (2005) 165–187

2 wks after surgery

Pre-surgical Post-surgical

Symptoms of oral tumors Dysphagia, wt. loss, oral bleeding, grossly

abnormal tissue, facial asymmetry and respiratory distress (maxillary tumors may impinge on the nasal passages)

Primary oral tumors in horses: Odontogenic

Pure epithelial, mixed epithelial and mesenchymal Slow growing masses

Osteogenic Soft tissue origin

FNA may not achieve representative samples to allow for an accurate diagnosis

Odontogenic tumors Calcified tumors

ODONTOMA=Dentinal tissue Combinations of all dental components=compound odontoma or

ameloblastic odontoma CEMENTOMA=Cementum Usually slow growing, hard focal mandibular or maxillary masses,

very radio-opaque Usually do not have draining tracts and the swelling exceeds that

of periapical abscessation Px depends on border definition and surgical resectability

Non-calcified tumors AMELOBLASTOMA

Derived from epithelium that forms enamel Do not induce connective tissue formation Freq expansile soft tissue mass with resorption of adjacent teeth and

boneP.M. Dixon, I. Dacre / The

Veterinary Journal 169 (2005) 165–187

Calcified massesOdontomas (including ameloblastic odontomas) and Cementomas

JAVMA, Vol 225, No. 9, November 1, 2004

Odontomas=Dentinal tissues

Rare, benign, locally expansive tumors of dental origin Odontomas are classified as hamartomas instead of neoplasms:

normal tissues in a chaotic arrangement: enamel, dentin, cementum and occas pulp

Complete surgical excision is curative Odontomas

epithelial and mesenchymal elements, induce connective tissue proliferation within the tumor (induction separates these from ameloblastomas)

Young, no known sex predilection, maxilla>mandible Classification

Compound-reported, rarely, in horses, dogs, and cattle have all the features of normal tooth formation Well-organized tooth-like structures known as denticles are often found

Complex-more differentiated than ameloblastic, w/ dental tissues arranged in a disorganized structure

Ameloblastic-most undifferentiated form, not common in horses

JAVMA, Vol 225, No. 9, November 1, 2004

Compound odontomas PE: Young animals (<1 year), epulis-like

growth or firm bony mass, no oral mucosal defect, non painful, no soft tissue swelling, may affect nasal airflow if maxillary

Rads: Well-marginated osseous-like mass encircling the alveolus, or centered around teeth. Tooth may be abnormally shaped and positioned, with indistinct alveolus. No evidence of lysis or fracture

JAVMA, Vol 225, No. 9, November 1, 2004

Compound Odontoma Histopathology

Multiple tooth-like structures and foci of normal bone; Denticles consist of a core of primitive mesenchyme resembling dental pulp, surrounded by a disorganized layer of odontogenic epithelium and a distinct zone of dentin, with an outer border that is disorganized and discontinuous of primitive ameloblasts

Aggressive surgical excision required for cure

Radiographic differentials: • Primary bone tumor

• Osteoma• Ossifying fibroma

• Primary dental tumor• Complex or compound odontoma• Ameloblastic odontoma• Ameloblastoma (usually not as mineralized)

JAVMA, Vol 225, No. 9, November 1, 2004

JAVMA, Vol 225, No. 9, November 1, 2004

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Complex Odontoma Less differentiated than compound odontomas Reported appearance in a case series:

Firm, smoothly rounded, raised mass Mass centered over the crown, with a radio-opaque rim

interspersed with lucent and mineralizing opaque areas (similar to that of enamel)

Normal dental sac structures present in all cheek teeth Differential diagnoses

Periapical abscessation Cyst Ossifying fibroma Malignant neoplasia-SCC and myomatous tumors Odontogenic tumors

Complex Odontoma Reported radiographic appearance

includes: Multilobulated masses within a well-

differentiated cyst-like structure Differentiated from compound odontomas in

that compound odontomas are organized into recognizable tooth structures

Locally aggressive, but complete surgical excision is curative

Complex Odontoma At surgery, mass was cystic containing white,

mineralized tissue suspended within HxPx: Odontogenic epithelium and stellate

reticulum. Material resembling cementum with nests of epithelial rests and chords of cells with early differentiation into ameloblastic cells with abnormal looking enamel matrix

Epithelial components: ameloblasts and stellate reticulum

Mesenchymal components: cementum and pulp

Cementomas=Cementum Rare odontogenic neoplasm of mesenchymal origin

(Not an odontoma since not epithelial component) Excessive deposition of cementum-like tissues Slow-growing tumor of cementoblasts, deposit

differentiated cemental matrix around the root, proliferation of cementoblasts and destruction of the lamina dura

Well-circumscribed, rounded, radio-opaque masses surrounding the roots of several incisors or premolars; deformation of surrounding alveolar bone and effacement of lamina dura (effacement of lamina dura differentiates this from hypercementosis)

Cementoma

Cementomas Histopathologically

Prominent, well-differentiated and demarcated proliferation of cementum-like material with collagen and abn lacunae surrounding normal dental structures, including dental pulp, dentin, and cementum

Etiology Possibly hereditary in humans, or due to a

reactive/hyperplastic response after periodontal trauma May occur any age (2-17 yr range) Differential: hypercementosis=non-neoplastic process

Excessive cementum accumulation in continuation with the normal radicular cementum, lamina dura is usu preserved

Usually not as disruptive

Non-calcified massesAmeloblastoma

Ameloblastoma Ameloblastomas: major Ddx for odontomas Characterized by a predominance of odontogenic

epithelium Large amts of odontogenic epithelial tissue, lack inductive

differentiation of dentin and enamel More common in the mandible of older horses, but can be

seen in foals Tend to be osteolytic and uni- or multilocular Keratinizing ameloblastoma: lg amounts of epithelial

keratin throughout the lesion Ameloblastic carcinomas: more differentiation toward

ameloblastic epithelium Ameloblastic odontomas: radiolucent or partially

mineralized with occas foci of enamel***

Histopathology on Jewel

Right mandible, teeth: The majority of the mass is composed of disorganized extracellular matrix associated with a dense band of inflamed fibrovascular connective tissue which contains a few small islands of epithelial cells consistent for rests of Malassez. Adjacent to this mass is a large tooth composed of degenerate, variably mineralized and disorganized, and possibly necrotic dentin. The mass is composed predominantly of matrix consistent for cementum, but is poorly organized into large aggregates with anastomosing, irregular cords. The matrix is pink with lacunae-trapped cells and multiple blue resting lines. In one section the matrix forms a plexiform arrangement with clear spaces in between creating a swiss-cheese like mass.� �

We shared slides with two pathologists and favor a diagnosis of cementoma. Cementoma is a benign lesion and does not metastasize. The lesion extends to the tissue margins.