Clinicopathological and immunohistochemical features of three pilomyxoid astrocytomas: comparative study with 11 pilocytic astrocytomas.

Pilomyxoid astrocytoma, first described by Tihan et al., was recently included as an established variant of pilocytic astrocytoma in the World Health Organization classification of CNS tumors. Histologically, it much resembles pilocytic astrocytoma, but monomorphic myxoid tumor of pilocytic cells with prominent angiocentric growth pattern without Rosenthal fibers or eosinophilic granular bodies is characteristic of pilomyxoid astrocytoma. Pilomyxoid astrocytoma is thought to be more aggressive with more frequent local recurrence as well as cerebrospinal spread. The authors recently encountered a case of pilomyxoid astrocytoma, therefore the purpose of the present study was undertake a retrospective review of pilocytic astrocytomas previously diagnosed during the past 10 years. Consequently, two of them were found to have histological features suggestive of pilomyxoid astrocytoma and both involved multiple recurrence, suggesting aggressive behavior in comparison to pilocytic astrocytoma. Therefore, knowledge of this entity is essential to surgical pathologists and clinicians for patient management.