Gliosarcoma: a case with unusual epithelial feature.

Astrocytic tumors, particularly gliosarcoma, may contain epithelial features in the form of trabecular, adenoid, papillary arrangement, and squamous metaplasia. A case of gliosarcoma with unusual epithelial feature is described. The patient was a 60-year-old male with frequent seizures. The mass was 4 cm and in the left frontal lobe. Trabecular or rarely adenoid arrangement of neoplastic astrocytes was present in the mucinous stroma, and there was a distinctive transition between the trabecular area and typical anaplastic astrocytoma. The tumor cells in the trabecular area showed positive immunostain for glial fibrillary acidic protein, but did not react with various kinds of cytokeratin. The sarcomatous area was undifferentiated and was not labeled by factor-VIII, desmin, and anti-smooth muscle actin. Occurrence and histogenesis of epithelial features in gliosarcoma are reviewed. The importance to recognize the existence of epithelial feature in malignant astrocytic tumor is emphasized.