Intracranial Germinoma in a Dog

Abstract

Neoplasms arising from primordial germ cells include the germinomas with their uniform cell type and associated lymphocytes, and a group of neoplasms of pluripotential nature, including embryonal carcinoma, teratoma, choriocarcinoma, and endodermal sinus yolk sac tum~rs . ' .~ .~ .~ . l l M ixtures of these types also occur. Gonadal and extragonadal examples of a given type appear to be identical. Germinoma in all of its sites, gonadal or otherwise, is primarily a midline neoplasm, supposedly reflecting the migratory path of primordial germ cells from yolk sac to germinal ridges.' Intracranially the usual sites are parapineal, hypothalamic, and basal (perichiasmal, suprasellar, or intrasellar). Germinomas (ovarian dysgerminomas, testicular seminomas), teratomas and a few mixed tumors are seen in the gonads of l o but are rare in intracranial sites. We have found only two acceptable cases of intracranial germinoma in the literature, one in the pineal region of a silver fox and another in the suprasellar area of a dog.3 Suprasellar teratoma with areas of germinoma also has been described in a dog9 In reviewing some old unclassified intracranial neoplasms in our collection, a perichiasmal germinoma was discovered in a four-year-old Doberman pinscher (sex not recorded) from which only the formalin-fixed brain had been submitted. Unfortunately, it is not known now if a complete necropsy was done. The dog had progressively worsening joint pain and unspecified terminal nervous signs. Appetite was good and the dog was afebrile.