Immunohistochemical evidence of neuronal and glial differentiation in retinoblastoma.

BACKGROUND The study sought to investigate the histogenesis of retinoblastoma. METHODS One hundred specimens of retinoblastomas were examined along with those of 18 astrocytic gliomas and 15 medulloblastomas to compare similarities of glial differentiation in retinoblastoma and the two types of brain tumour. Employing avidin-biotin immunoperoxidase technique, antibodies were applied against neuron specific enolase (NSE), glial fibrillary acidic protein (GFAP), and S-100 protein (S-100). RESULTS Most rosettes and fleurettes, and some undifferentiated cells in retinoblastomas were NSE positive, but GFAP and S-100 negative. GFAP and S-100 positive cells in retinoblastomas were detected mostly in well differentiated glial cells which were interpreted as reactive or non-neoplastic cells. Some of the GFAP and S-100 positive cells in retinoblastomas were defined as tumour cells that resembled neoplastic astrocytes in astrocytic gliomas and medulloblastomas. CONCLUSION Retinoblastoma may arise from primitive bipotential or multipotential cells capable of neuronal and glial differentiation.