Abstract.A 10-year-old, male, Shih-Tzu dog presented with swelling of the right lower jaw caused by a mass arising from the right mandibular gingiva. Radiographic examination revealed bone lysis of the right wing of the mandible. Histopathologically, the growth was characterized by indistinctly lobulated nests, islands, and strands of proliferating odontogenic and squamous epithelial cells, intermingled in close association with large numbers of irregular extracellular deposits of amyloid and amorphous calcified substance. Immunohistochemically, both epithelial components stained strongly positive for cytokeratin (AE1/AE3); the squamous epithelial cells also reacted strongly with neuron-specific enolase (NSE) and S-100 protein, whereas the odontogenic epithelial cells displayed weak immunoreactivity to NSE and partial reactivity to S-100 protein. The amyloid deposits were AE1/AE3-negative. The growth was diagnosed as an amyloid-producing odontogenic tumor.

The characteristics of 163 spontaneous neoplasms diagnosed in 150 necropsied zoo mammals, birds, and reptiles at Taipei Zoo during 1994-2003 were analyzed. Histopathology and immunohistochemistry were employed to classify the tumor types. A total of 2657 necropsied zoo animals, including 1335 mammals, 873 birds and 449 reptiles led to the diagnosis of tumor in 8.1% (108/1335), 4.2% (37/873) and 1.1% (5/449) of cases, respectively. The most predominant type of tumors in mammals was mammary gland tumors (12.0%, 13/108), followed by uterine smooth muscle tumors (10.2%, 11/108), lymphosarcoma (9.3%, 10/108), hepatocellular carcinoma (8.3%, 9/108), and cutaneous squamous cell carcinoma (6.5%, 7/108). The avian neoplasm with the highest incidence was lymphosarcoma (35.1%, 13/37). Five individual neoplasms were found in different reptile species. The overall incidence of malignant tumors (63.8%, 104/163) was greater than that of benign tumors (36.2%, 59/163). Immunohistochemistry characterization of these tumors revealed a histogenesis which is similar to that seen in domestic animals and humans.

Abstract.A case of fibrosarcoma with lung and lymph node metastases in a 54-year-old female Asian elephant (Elephas maximus) is described. After pododermatitis of 2 years duration in the right forefoot, a mass developed in the lateral toenail. At postmortem, metastasis to the right axillary lymph node and both lungs was noted. Microscopic examination of primary and metastatic sites revealed infiltrating bundles of spindle cells, with fairly distinct cell borders, variable amounts of eosinophilic cytoplasm, and elongate or oval nuclei. Tumor cells were often arranged in interwoven bundles and herringbone patterns. Mitotic figures were numerous and frequently bizarre. The diagnosis of fibrosarcoma with lung and lymph node metastases was made on the basis of histologic features and positive immunohistochemical staining for vimentin.A 54-year-old female Asian elephant (Elephas maximus) housed at the Taipei Zoo in North Taiwan had a 2-year history of pododermatitis of the right forefoot. The lesion had been treated by surgical debridement, irrigation with 5% Povodine iodine, and soaking using 5% copper sulfate solution. Clinical signs had slowly improved, the lesion resolved, but in the next 6 months a rapidly growing mass developed proximal to the lateral toenail of the previous site of pododermatitis. The mass was red-black and cauliflower-shaped with a necrotic and irregular hemorrhagic skin surface (Fig. 1). The animal was lame in the affected foot. A biopsy was performed under general anesthesia, and histologic evaluation indicated a sarcoma with necrotic foci and an ulcerative surface. The tumor cells stained positive for vimentin and negative for cytokeratin (AE1/AE3), desmin, smooth muscle ␣-actin, S-100, and factor VIII-related antigen. The animal died after 3 days recumbency.Necropsy revealed marked swelling of the right forefoot due to the mass with an ulcerative and cauliflower-shaped appearance. The tumor was approximately 34 ϫ 24 ϫ 10 cm 3 and was more extensive than it had appeared on external inspection. On the transverse section, the tumor was white, firm, and multilobulate with multifocal hemorrhage and necrosis in the soft tissue under the skin. The tumor had metastasized to the right axillary lymph node; the area was extremely swollen. The metastatic lesion was 12 ϫ 7 ϫ 2 cm 3 , firm, multilobulate, with multiple areas of necrosis on the cut section. Multiple nodules, 0.5-5 cm in diameter, were present in both lungs. The cut surface of nodules was graywhite and glistening. Postmortem radiography of the lungs