Salivary Gland Epithelial-Myoepithelial Carcinoma with High-Grade Transformation in a Dog.

An 8-year-old male neutered standard dachshund was presented with a slowly growing mass in the left submandibular salivary gland. Histopathological examination revealed a tumour that was composed of bilayered duct-like structures with an inner layer of ductal cells and an outer layer of clear cells. Both inner and outer cells in the greater part of the tumour exhibited low to moderate atypia and low mitotic activity. However, a focal area towards the periphery showed enhanced cellular atypia and mitotic activity in tumour cells. Immunohistochemically, the outer layer of clear cells expressed myoepithelial markers, while the inner layer cells were positive for a luminal epithelial marker. No local recurrence or lymph node or distant metastasis was observed 18 months following surgery. Based on the morphology and immunohistochemical findings, a final diagnosis of epithelial-myoepithelial carcinoma with high-grade transformation was made.

Spontaneous poorly differentiated carcinoma with cells positive for vimentin in a salivary gland of a young rat.

Spontaneous salivary gland tumors in rats are rare. The authors report a poorly differentiated carcinoma of a submandibular gland in a ten-week-old rat that was positive for vimentin. Microscopically, the neoplastic cells showed a diffuse growth pattern in most areas of the tumor mass and a nestlike structure in a part of the peripheral area. Immunohistochemically, the cells were positive for keratin and vimentin but not for alpha-smooth muscle actin. Ultrastructurally, desmosome-like structures were observed. Based on these findings, the tumor was diagnosed as a poorly differentiated carcinoma. The origin of the neoplastic cells would be either acinar or ductal cells. This suggests that acinar or ductal cells have the potential to transform into vimentin-expressing cells.

67Gallium citrate scintigraphy to assess metastatic spread in a dog with an oral melanoma.

Gallium scintigraphy was used to evaluate therapeutic response in a 10-year-old, male, Dutch sheepdog, suffering from an oral melanoma. Treatment was performed with a combination of carboplatin and hypofractionated radiation. Nineteen weeks after radiation therapy, the left submandibular lymph node was surgically removed because of metastatic disease. Thirty weeks after radiation therapy, 67Gallium scintigraphy was performed to assess for residual disease and metastasis. Increased uptake in the right submandibular lymph node area was noted and identified as a melanoma metastasis on cytology. Surgical excision was performed. Twenty-one weeks later, the dog was euthanased because of advanced pulmonary metastases. This report of a case of oral melanoma illustrates the advantages of 67Gallium scintigraphy in monitoring for the presence of metastatic disease and effectiveness of therapy.

Carcinoma of the submandibular salivary glands with multiple metastases in a cat.

A 9-year-old neutered male domestic shorthair cat was presented because of coughing, dysphagia, and prostration. Examination revealed firm bilateral anterocervical swellings extensively adhered to the surrounding tissues. Anisocoria with left-side miosis was also evident. X-ray and ultrasound examinations along with a fine-needle aspiration biopsy were performed. Slides were stained with May-Grünwald Giemsa, and a diagnosis of salivary gland carcinoma was made. At surgery, the tumor was found to involve both submandibular salivary glands as well as adjacent lymph nodes and surrounding tissues. The cat was euthanized and necropsy was performed. The majority of tissues and organs examined histologically, including mandibular and retropharyngeal lymph nodes, soft palate, laryngopharynx and lungs, contained neoplastic cells whose appearance was consistent with adenocarcinoma. Bilateral salivary adenocarcinoma has not previously been reported in cats, and extensive metastases are rare.

Extraskeletal osteosarcoma of the mandibular salivary gland in a dog.

A 14-year-old spayed female shepherd/collie crossbred dog had a 6 x 4-cm mass excised from below the right ear. The partially encapsulated, neoplastic mass had a necrotic core and was embedded in the mandibular salivary gland. Histologically, the mass was composed of numerous multinucleate giant cells and large, oval, pleomorphic cells that produced osteoid. Neoplastic cells were immunoreactive for vimentin and actin but not for keratin, desmin, or S-100 protein. At postmortem examination 1 month later, an 11-cm spherical mass had recurred at the surgical site, and there were metastatic nodules in the lungs, ipsilateral mandibular lymph nodes, and kidney. The tumor was diagnosed as an osteosarcoma of the mandibular salivary gland with pulmonary, lymphatic, and renal metastasis. In addition, a 17-year survey of canine salivary-gland neoplasms revealed that most were adenocarcinomas or carcinomas.

Naturally occurring mucoepidermoid carcinoma in the submandibular salivary gland of two mice.

Mucoepidermoid carcinomas in two mice were investigated histologically, immunohistochemically and ultrastructurally. The neoplastic cells showed divergent differentiation into periodic acid-Schiff-positive mucous cells, keratin-positive squamous cells, and cells with both mucous granules and sheaves of tonofilaments. Gland formation and keratinization were not observed. At the periphery of tumour cell nests, some cells were immunolabelled for smooth muscle actin or contained concentrated thin filaments, and these observations were interpreted to indicate that murine mucoepidermoid carcinomas are associated with both myoepithelium and duct epithelium.

Mast cell tumor in the mandibular salivary gland in a dog.

A mast cell tumor in the mandibular salivary gland was diagnosed in a 9-year-old English Setter. Dense infiltrating sheets of mast cells were present within the mandibular salivary gland, the medial retropharyngeal lymph node and in two subcutaneous masses on the flank. The salivary gland, lymph node, and masses were excised. The dog was treated postoperatively with the histamine receptor antagonist, cimetidine and the alkylating agent, chlorambucil. The tumor recurred at the angle of the mandible 4 months later and the dog was killed.