This case is currently being reviewed. The case report will be published in its entirety when complete.History: The animal presented with a suspected tooth root abscess in October 2006. Pre-operative blood work was within normal limits and the animal was taken to surgery for extraction of the first right maxillary pre-molar and the second and third molar. This was followed with a post-operative course of clindamycin. Swelling and bleeding persisted in the oral cavity and over the right side of the nose and face after surgery and the extraction sites did not heal. Over the next month bleeding from the oral and right nasal cavity increased. A radiograph revealed osteolysis of the right maxilla and a soft tissue opacity at that site. Euthanasia was elected. The medical history was significant for an episode of endometriosis in 2007 for which an ovariectomy was performed at that time.

Gross Description:  

The animal was in good body condition and weighed 4.14 kg. Fat stores, muscle mass and hydration status were all adequate. Marked dental tartar was present on all remaining teeth, but most molars had been extracted. A 0.5 cm x 4 cm long oronasal fistula created a communication between the right nasal cavity and the mouth at the site of the most recent surgical extractions. Upon reflection of the facial skin, a 2.5 cm diameter mass of soft grey tissue was present in the right maxillary sinus and the bone of the overlying maxilla was eroded away.

Histopathologic Description:

The mass is composed of a dense population of polyhedral to oval neoplastic cells that form nests, packets and cords separated by trabeculae of dense fibrovascular connective tissue. Frequently, within these nests and packets, the cells form small acinar and ductular structures. The cells are approximately 15-20 microns in diameter and contain oval, centrally placed nuclei with dispersed chromatin and rarely apparent nucleoli. Anisocytosis and anisokaryosis are mild and mitotic figures are rare. The mass is well demarcated and unencapsulated with an invasive border From which tumour cells infiltrate irregularly into the surrounding soft tissue, bone and around blood vessels. Neutrophils and lymphocytes are present at the tumour border. Multifocal aggregates of deeply eosinophilic, polyhedral cells with indistinct borders containing small round nuclei (squamous differentiation) punctuate areas of the mass. In areas where the mass infiltrates bone, there is effacement of the alveolar bone (where the tooth roots of the extracted teeth would have rested). Tumour cells replace all cells in the marrow cavities and invade bone of the maxilla. Focal aggregates of osteoblasts and small groups of 3-5 osteoclasts are noted. The cell cytoplasm stains positive for pancytokeratin in some areas, particularly the glandular and ductular structures. They are negative for vimentin.

Morphologic Diagnosis:  

Nasal Adenocarcinoma with Squamous Differentiation, Right Nasal Cavity and Maxillary Sinus

Lab Results:  

CBC and biochemistry panel were within normal limits.

Contributor Comment:  

While periodontal disease was present in this animal, the cause for the suspected tooth root abscess was actually an invasive growth of a nasal adenocarcinoma into the maxilla that also invaded and replaced the alveolar bone and tooth roots on the right upper arcade. Nasal adenocarcinoma is an uncommonly reported tumour of the upper respiratory tract in non-human primates. There are few reports of nasal adenocarcinomas or carcinomas occurring in non-human primates in the literature. 1,2,3 In humans, it has been associated with various occupational exposures to inhaled substance such as the fine particulate matter found in the woodworking and textiles industries and fumes and vapors common to the chemical industry. 4,5 Exerpimental work in macaques has also shown that ozone may act as a toxic inducing agent when in contact with the nasal mucosal epithelium. 6 Adenocarcinomas are characteristically composed of glandular structures that usually contain some degree of secretory product. The most common forms are tubular, tubulopapillary and acinar. Mixed patterns are frequent. Low-grade tumors have glandular spaces or papillary fronds lined by cuboidal to columnar cells in a single layer with a round to oval nucleus and inconspicuous nucleoli whereas high- grade tumors have irregular glandular spaces, more solid sheets of cells and a high mitotic rate with cellular pleomorphism and nuclear atypia. Mucus is the most common secretion in adenocarcinomas and often there is retention creating cystic spaces. In addition to tubular, tubulopapillary and acinar classifications, adenocarcinomas may be further classed as mucinous or adenocarcinomas with marked desmoplasia (fibrous response). Adenocarciomas with squamous metaplasia or differentiation is reserved to describe tumors with minor portions containing regular squamous differentiation, as in this case. Adenosquamous carcinoma refers to tumors that are typically highly invasive and have prominent intermixing of adenocarcinomatous and malignant squamous cell components.7

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