Abstract
A juvenile magpie (Pica pica) presented to our clinic after being found in a garden attacked by crows. On clinical examination, the magpie was depressed, exhibited tremors, and emaciated. A one-centimeter tumor was visible in the left ear. Due to the poor condition of the magpie, euthanasia was elected. Upon necropsy, the left acoustic meatus was filled completely by the mass, which also expanded below the processus postorbitalis into the orbit and bulged out of the soft palate. The tumor was firm, white in color, and had a smooth surface. In the histopathologic examination the tissue was formalin fixed, paraffin embedded, and routine haematoxylin and eosin stained. The mass was diagnosed as a malignant blastoma. Upon immunohistochemistry staining, the tumor expressed smooth muscle actin and was negative for desmin and cytokeratin. These results indicate a malignant tumor, possibly of mesenchymal origin. The expression of smooth muscle actin leads to the presumption of a leiomyosarcoma although the desmin was negative. In cases of leiomyosarcomas reported in the literature both were always positive.1,2,4 The origin of the tumor was macroscopically not locatable, but possible origins include the smooth muscles of the external acoustic meatus skin or the Musculus columellae, the tensor of the tympanic membrane. The muscular layer of blood vessels could also be a possible origin. In our case there were no macroscopically visible metastases in other organs although metastatic leiomyosarcomas are reported in birds.1,3
Literature Cited
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