Teratomas are complex tumors with recognizable elements of multiple germ layers in various stages of maturation and are thus composed of multiple tissues foreign to the part of the body in which they arise. Testicular teratoma has been most commonly reported in the horse and is extremely rare in other animals, in which teratomas generally develop in the ovary. Testicular tumors are rare in cats, and only two cases have been reported; both were Sertoli cell tumors.
A case has been described of a spontaneous teratoma in the unilateral cryptorchid testis of a cat. In this case, a 2-year-old male American Shorthair cat was referred to an Animal Hospital with distention of the abdomen. In an exploratory laparotomy, a 6-cm mass (approximately 600 g) was found in the posterior portion of the abdominal cavity, and it was surgically removed together with the omentum. Because a unilateral testis had been found in the scrotum at the time of a previous orchidectomy, the mass in the abdominal cavity was suspected to be a cryptorchid testis. Pure immature teratoma is extremely rare. In the present case, based on the clinical history of the cat and the results of histopathologic and immunohistochemical examination, the tumor was diagnosed as teratoma in the unilateral cryptorchid testis. The abdominal masses observed on ultrasonography were presumed to be metastases to the peritoneum.
In a second case, a 3-year female-neutered domestic shorthair cat presenting with exophthalmos and an ipsilateral subzygomatic soft tissue mass lesion is described. Magnetic resonance imaging of the mass was performed followed by complete surgical excision. The mass was determined to be a retrobulbar teratoma and complete resection was curative. Teratomas are rare germ-cell tumours that uncommonly form in extragonadal sites. A retrobulbar location has not been previously reported in the cat and should be considered a rare cause of exophthalmos in this species.
In humans, teratomas most often metastasize through the lymphatic vessels, but in the absence of a postmortem examination in the case described above, they were unable to determine whether metastasis was via lymphatics or implantation.
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