Gliosarcoma: cytopathologic characteristics on fine-needle aspiration (FNA) and intraoperative touch imprint

Gliosarcoma (GS) is a rare subtype of glioblastoma multiforme (GBM), which shows a dimorphic population of glial and mesenchymal elements. The cytopathology of GS to our knowledge has not been previously described. Although prognostically insignificant within the group of GBM, an accurate recognition of this subtype may help to rule out other morphologically similar primary and metastatic central nervous system (CNS) neoplasms. Thirteen cases of histologically confirmed GS with concomitant touch imprints (TI) or prior fine-needle aspiration (FNA) were retrieved from the files of The Johns Hopkins Hospital (1985-2002). A comprehensive review of the clinico-radiologic, cytologic, and histologic material was undertaken to define the morphologic characteristics of GS. Material was obtained via computerized tomography (CT)-guided needle biopsy. Slides were stained with DiffQuik and/or hematoxylin and eosin (H and E) stains. Smears were highly cellular and showed a high-grade neoplasm with glial and mesenchymal elements. The latter component, however, predominated and showed a variety of phenotypic patterns, which included fibrosarcoma-like, rhabdoid type, osteoclastic giant cell type, undifferentiated type, and tumor with heterologous components (such as chondroid or osteoid tissue). A rich arborizing capillary network was evident, as were a high mitosis/karyorrhexis index and foci of necrosis. The glial component consisted of pleomorphic round to oval nuclei and numerous gemistocytes embedded in a fibrillary stroma.