Malignant schwannoma in a red deer (Cervus elaphus)

Pigmented tumors in fallow deer ( Dama dama): 11 cases

Pigmented tumors have been reported infrequently in captive deer. We document herein the clinical progression and gross and histopathologic features of pigmented tumors diagnosed as melanoma and pigmented schwannoma in 11 white fallow deer ( Dama dama). Affected animals were part of a captive herd maintained at a drive-through park in southern Oregon and were 5-17 y of age during the study period (2004-2013). Primary lesion locations included periocular, perineal, and neck tissues, with cutaneous and internal metastases later identified at autopsy in some cases of malignant melanoma. Diagnoses included 7 malignant melanomas, 2 benign melanomas, and 2 pigmented schwannomas. Diagnosis of melanoma was based on typical histomorphologic features, and final diagnosis of pigmented schwannomas was based on histomorphologic features with negative staining for melan A and positive staining for laminin. Metastasis was found in 3 of 7 cases diagnosed as malignant melanoma; 2 had extensive pulmonary involvement and resulted in euthanasia of the animal; 1 animal developed eyelid and ear lesions that also resulted in euthanasia.

Oral squamous cell carcinoma in a red deer (Cervus elaphus)

We describe the pathomorphologic and immunophenotypic characteristics of an oral squamous cell carcinoma in a 13-yr-old, free-ranging red deer (Cervus elaphus) in Lower Saxony, Germany.

Malignant schwannoma in an American buffalo (Bison bison bison)

A case of a malignant schwannoma in a 20-year-old male American buffalo (Bison bison bison) from the Grand Park Zoo, Gyeonggi Province, Republic of Korea is reported. The animal showed no apparent clinical signs before death except for wound on the neck. Grossly, neoplastic nodules of various sizes were observed on the skin, lung, heart, liver, stomach, mesentery and kidney. Histologically, the neoplastic nodules were composed of fusiform cells that formed multidirectional bundles. The tumour cells were arranged in interlacing bands and bundles. The nuclei were atypical, hyperchromatic, with blunt or round ends. In addition, few mitotic figures were observed in the skin, lung, heart, liver, stomach, intestine and kidney. Several immunohistochemical stains, e.g. vimentin, cytokeratin (CK), smooth muscle actin (SMA), S-100 and HMB45, were used in an attempt to differentially diagnose the tumour. The neoplastic cells tested positive to S-100, but negative to vimentin, CK, SMA and HMB45. Based on the above findings, this case was diagnosed as a malignant schwannoma. To the best of our knowledge, this is the first report of a schwannoma in an American buffalo (B. b. bison).

Multicentric malignant Schwannoma in a crossbred cow

Multicentric malignant Schwannoma in a crossbred cow is described. Multiple and solitary nodules of varying sizes were seen to be distributed throughout the body of the animal, mainly along the peripheral nerves supplying the muscles of the thoracic and abdominal regions and the skin. Multiple nodules were also observed in the hilus of the liver. The mediastinal lymph nodes were replaced by a large solitary tumorous mass. Multiple neoplastic linear cords with small nodules were observed on the pericardium. Histologically, the nodules showed mainly densely packed, spindle-shaped cells arranged in short interwoven bundles and whorls (Antoni type A pattern). Stellate, spindle-shaped and round or oval tumour cells proliferated haphazardly within the loose texture of a collagenous matrix (Antoni type B pattern). Immunohistochemically, in both Antoni type A and type B areas, neoplastic cells reacted with antibodies against S-100 protein. Based on the metastasis of the tumour to the lymph nodes and on histology, the neoplasm was diagnosed as a multicentric malignant Schwannoma.

Point mutation of neu oncogene in animal peripheral nerve sheath tumors

Thirty-four peripheral nerve sheath tumors of four domesticated animal species were characterized and assayed for point mutation of the neu oncogene. Based on their morphoimmunophenotype, 32 tumors were classified as schwannomas. Schwannoma morphology was characterized by the presence of Antoni type A and B pattern and immunoreactivity for S-100 protein and vimentin. Two anaplastic and metastatic tumors originating from spinal cord root, immunonegative for S-100 protein and positive for vimentin, were classified as malignant peripheral nerve sheath tumors (MPNSTs). Four malignant schwannomas and two MPNSTs expressed a point mutation of the neu oncogene by the polymerase chain reaction-restriction fragment length polymorphism method. The finding of neu oncogene mutation could be a useful diagnostic genetic marker in the malignant form of peripheral nerve sheath tumors in animals.