Histopathological and immunohistochemical characteristics of ventricular ependymoma in a goat

Abstract

Ependymomas as primary central nervous system neoplasms are occasionally observed in human infants however; they are rare in animals. A three-year-old male goat was presented with clinical neurological signs. At necropsy, a 3×2×2 cm, bulging, white-grey-to red, soft mass extending into the left lateral ventricle of brain was observed. Microscopically, the mass with densely cellular population was nonencapsulated, mostly containing cuboidal-columnar neoplastic cells with pseudo-rosettes formation. Mitotic figures were rare and malignancy indexes were not observed. Neoplastic cells were immunohistochemically positive for Glial Fibrillary Acidic Protein (GFAP), S-100, and vimentin; however, they did not express Cytokeratins. On the basis of the location, histologic and immunohistochemical findings, the tumor was diagnosed as an ependymoma.

Ependymoma in a dwarf goat

“…The tumour's association with the ventricular system supports the diagnosis, as it is a typical feature for the bulk of ependymomas [3][8] [13], though this one extended very far until the medulla of the cerebellum. The clinical findings of recumbency and development of an opisthotonus are consistent with the tumour location, and go with the neurological signs that have been described previously in a goat with ependymoma [7]. Considering information about ependymomas in other species, the animal's increased age matches former accounts [8] [27].…”

“…In humans, tumour reactivity to S100 protein with perivascular accentuation has been described [26]. The immunophenotype in the presented case is similar to the previously reported goat [7]. It represents also an important point for the exclusion of an oligodendroglioma as the main differential diagnosis of cellular ependymomas.…”

“…The negative result for the CNPase-antibody also constitutes a hint in opposition of the diag-nosis of an oligodendroglioma. In contrast to the intense vimentin staining in the previously published goat [7], the immunolabelling of this intermediate filament in caprine ependymomas may be variable. According to the literature, most ependymomas in animals show at least slightly positive staining for vimentin but without any evidence of a particular pattern [2] [8].…”

“…According to reports concerning ependymomas in humans, it lacks widely a tumour cell arrangement radially around blood vessels and formation of perivascular pseudorosettes with characteristically nuclear-free zones, and/or true ependymal rosettes [18]. Cellular ependymomas have been described occasionally in dogs [8], and the morphological findings described in a previous case of an ependymoma in a goat are suggestive of a cellular subtype, too [7]. Cellular ependymomas are not considered in the current veterinary WHO classification [13], but are listed in the previous edition of the WHO classification of human CNS tumours [18].…”

“…A 6-month-old male Holstein calf was diagnosed with an ependymoblastoma [22], but some authors determined the term as imprecise and unspecific and want it disestablished [11]. In small domestic ruminants, there is, to the best of the authors' knowledge, only a single case report in a sheep [4] and in a 3-year-old male native Iranian goat [7], respectively.…”