Malignant neoplasm of the perineural sheath retrobulbar and intracranial in dog: case report

ABSTRACT Tumors of the perineural sheath are uncommon in domestic animals. We report the case of a 5-year-old female dog with a history of increased volume in the retrobulbar region of the right eye (RE) three weeks ago. The clinical examination revealed a presence of a right retrobulbar neoformation with cranial ocular globe displacement. In the examinations carried out during hospitalization, it was not possible to locate a source and an extension of the neoformation. The animal died of cardiorespiratory arrest and was referred to an autopsy. The macroscopic evaluation revealed a whitish neoformation fixated to the base of the skull in a seal region, with a possible non-III origin of cranial nerves, infiltrating non-encephalon at the height of the hypothalamus, extending caudally towards the brainstem and cranially to the orbit right, compressing RE. Microscopically it consisted of short bundles intertwined or enovelados of spindle cells with discrete to moderate pleomorphism, alternating to areas of multifocal necrosis, compatible with tumor of the perineural sheath. Immunohistochemical examination showed weak marking for S100 and GFAP and positive marking for vimentin, indicating malignancy.