Pleomorphic xanthoastrocytoma

Pleomorphic xantho-astrocytoma (PXA) is a relatively rare brain tumor of adolescents and young adults characterized by its superficial location with frequent involvement of the meninges, and its slow growth despite features of histological atypia. The authors present a retrospective immunohistochemical analysis of 8 surgically treated cases in order to determine the expression of glial and neuronal markers, and to assess the proliferating cell fraction. The study population comprised 1 female and 7 male patients with a mean age of 26.7 years, most tumors being located in one of the temporal lobes. Epilepsy predominated as a presenting symptom. Five cases were assigned WHO graded II, while the diagnosis of anaplasia (WHO grade III) was established in three, based either on elevated mitotic counts or the presence of necrosis. Immunostaining with the proliferation marker MIB-1 was present in 2.05% of cells in the former groups, while 4.66% showed labeling in the latter. Postoperative follow-up averaged 6.7 years, with only one recurrence of an anaplastic tumor. All tumors expressed some amount of glial fibrillary acidic protein and were shown to elaborate a characteristic pericellular reticulin network. There was focal reactivity for alpha-1-antitrypsin, but neither the monocyte-macrophage associated antigen CD68 nor lysozym could be detected in neoplastic cells. In 7 cases, scattered individual tumor cells exhibited synaptophysin positivity. The authors review problems and prognostic issues of the histologic diagnosis of anaplasia occurring in some 20% of the cases. A possible dysontogenic origin of PXA and its nosologic relationship to the so-called desmoplastic neuroepithelial tumors of infancy are discussed. This is the first study of pleomorphic xanthoastrocytoma in the Hungarian literature.