JPC SYSTEMIC PATHOLOGY
DIGESTIVE SYSTEM
October 2018
D-N01

Signalment (JPC #1698960): Adult boxer

HISTORY: The animal presented with an oral mass

HISTOLOGIC DESCRIPTION: Gingiva: Expanding the subepithelial connective tissue, elevating the overlying hyperplastic mucosa, and extending to cut borders is an unencapsulated neoplasm composed of loosely arranged streams of evenly spaced spindle to stellate cells separated by an abundant collagen matrix. Neoplastic cells have indistinct borders with moderate amounts of eosinophilic fibrillar cytoplasm. Nuclei are irregularly oval to elongate with finely stippled to hyperchromatic chromatin and an indistinct nucleolus. The mitotic rate is less than 1 per 10 high power fields. Focally within the neoplasm is an island of osseous metaplasia composed of immature woven bone. Multifocally there are also few aggregates of homogenous, eosinophilic material up to 40 um in diameter (dental hard substance). There are multiple small subepithelial and perivascular accumulations of plasma cells, fewer lymphocytes and occasional neutrophils. The overlying epithelium is moderately hyperplastic forming anastomosing rete ridges up to 2 mm in length with moderate acanthosis, spongiosis, multifocal epithelial intracellular edema, multifocal hyperkeratosis, neutrophilic exocytosis, and a focal area of erosion.

MORPHOLOGIC DIAGNOSIS:  Gingiva:  Peripheral odontogentic fibroma, boxer, canine.

SYNONYM:  Fibromatous epulis of periodontal ligament origin

Signalment (JPC #2749933):  A dog

HISTORY:  Mass from the mouth

HISTOLOGIC DESCRIPTION:  Gingiva:  Expanding the subepithelial connective tissue and multifocally extending from the hyperplastic mucosa, is an unencapsulated, infiltrative, moderately cellular neoplasm composed of anastomosing cords, ribbons, and trabeculae of well-differentiated polygonal cells separated by an abundant dense and well vascularized stroma.  Neoplastic cells have distinct cell borders, a moderate amount of eosinophilic granular cytoplasm, and irregularly round to oval nuclei with finely stippled chromatin and 1-2 magenta nucleoli.  The mitotic rate is 1 per 10 high power (40x) fields.  Along the periphery of trabeculae neoplastic cells palisade, and often have antibasilar nuclei with frequent basilar cytoplasmic clearing, while nonbasilar neoplastic cells often have prominent intercellular bridges (odontogenic epithelium).  Multifocally within cords and trabeculae are variably sized cysts filled with amphophilic flocculent material, few foamy macrophages and sloughed epithelial cells.  Multifocally infiltrating the subepithelial connective tissue are large numbers of macrophages, lymphocytes, plasma cells and neutrophils.  Diffusely the mucosal epithelium is hyperplastic with prominent rete ridge formation, acanthosis and spongiosis.  There is a focal mucosal ulceration with replacement by eosinophilic cellular and karyorrhectic debris, abundant viable and degenerate neutrophils, fibrin, hemorrhage, and reactive fibroblasts, and multifocally moderate numbers of neutrophils transmigrate the mucosal epiothelium.

 GENERAL DISCUSSION:

 GROSS FINDINGS:

LIGHT MICROSCOPE FINDINGS:


DIFFERENTIAL DIAGNOSIS:

For oral/gingival mass:

COMPARATIVE PATHOLOGY:

REFERENCES:


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