Case Report: Amyloid-Producing Odontogenic Tumor With Pulmonary Metastasis in a Spinone Italiano-Proof of Malignant Potential

Abstract

A 1-year-old male Spinone Italiano dog was treated for an amyloid-producing odontogenic tumor on the right maxilla with a cytoreductive surgery followed by a definitive radiation protocol. Six years later, the dog presented for a new mass on the rostral mandible as well as a lung nodule without recurrence of the original maxillary tumor. Both the mandibular mass and the lung nodule were histologically confirmed to be amyloid-producing odontogenic tumor based on the appearance of sheets and cords of the odontogenic epithelium disrupted by amorphous extracellular amyloid. This case illustrates the metastatic potential for amyloid-producing odontogenic tumor in dogs and asynchronous occurrence of multiple APOTs in the oral cavity.

Keywords: amyloid producing odontogenic tumor; dogs; neoplasia; odontogenic tumor; pathology—head and neck neoplasms.

Figure 1

Primary APOT of the rostral maxilla, dog. (A) Axial CT image of the skull at the level of 106 showing the maxillary mass. (B) HE, 40×. In the peripheral region of the mass (left of image), odontogenic epithelial cells are organized in sheets and cords. Lower cellularity in the central portion of the mass is the result of extracellular deposits of amorphous eosinophilic material (presumed amyloid) that multifocally coalesce to resemble osteoid/dentinoid matrix (arrows). (C) HE, 400×. The neoplastic epithelial cells have basilar to acanthomatous morphology. Architecture is less distinct where cells have abundant cytoplasm and produce extracellular amyloid (double arrows). Mitotic figures (yellow arrows) are common among the basal cells although nuclear atypia was low to moderate.

Figure 2

Second APOT on the rostral mandible, dog. (A) A mass lingual to the right mandibular incisors and canine expands the rostral mandible. (B) HE, 40×. An expansile intraosseous mass displaced a rim of atrophied mandibular bone (arrows) and the overlying gingiva is unremarkable in this section. (C) HE, 200×. Cords of small basilar epithelial cells (arrowheads) and sheets of larger polygonal cells (double arrows) are occasionally distinct although much of the tissue architecture is disrupted by abundant extracellular eosinophilic amyloid, which is multifocally mineralized (arrows). The clear space surrounding the mineralized foci is artifact of processing. (D) HE, 200×. In some areas of the tumor, neoplastic epithelial cells had ghost cell morphology. The abundant keratinized cytoplasm can be difficult to differentiate from lighter pink amyloid. (E) IHC for pancytokeratin AE1/AE3, DAB chromogen, 200×. Sheets and cords of epithelial cells (arrowheads) have moderate to strong positive labeling of the cytoplasm, including cells that are among the amyloid. The amyloid (*) is negative, and the mineralized foci are dark blue (yellow arrows). (F) IHC for vimentin, DAB chromogen, 200×. Sheets and cords of epithelial cells (arrowheads) have minimal or no positive labeling of the cytoplasm, in contract to the supporting connective tissues. The amyloid (*) is negative, although some cells surrounding the amyloid have positive labeling. The mineralized foci are dark blue (yellow arrows). (G) Congo red, 200×. Extracellular amyloid deposits are congophilic (*), having deep red positive staining. (H) Axial CT image of the mandibular mass.

Figure 3

Metastatic APOT in the lung, dog. (A) Axial CT image of the right cranial lung lobe mass indicated by the circle. (B) Axial CT image of the nodule noted in the left cranial lung lobe indicated by the arrowhead. (C) HE, 20×. The mass (left of image) is well demarcated, and adjacent lung tissue (right of image) is minimally compressed with intact architecture. The lung tumor has areas of purple cellularity intermingled with abundant eosinophilic material that coalesces into trabeculae. (D) HE, 400×. As in the original oral APOT), sheets of cells are disrupted by extracellular amyloid (*). (E) HE, 200×. The lung tumor had plexiform branching of cords of small polygonal cells with areas of necrosis (N). The amyloid (*) was less intensely eosinophilic yet distributed in the same pattern as the smallest deposits of brightly eosinophilic, osteoid-like matrix (arrows). (F) HE, 600×. Mitotic figures (arrow) were common, and nuclei had a moderate degree of nuclear atypia. (G) Congo red, 20×. Patchy areas of the extracellular material are congophilic with red staining, consistent with amyloid (arrows). (H) Congo red, 400×. Congophilic extracellular amyloid stains red. (I) Masson's trichrome, 20×. Much of the extracellular material is bright blue with trichrome, consistent with collagen matrix. (J) Masson's trichrome, 400×. The amyloid deposits (*) are pale blue while collagen fibers are bright blue (arrows).