Immunocytochemical evidence of molecular photoreceptor markers in cerebellar medulloblastomas.

With the use of antisera against bovine retinal S-antigen and bovine opsin the authors demonstrate that in cerebellar medulloblastomas certain tumor cells display immunocytochemical properties characteristic of retinal photoreceptors and pinealocytes. S-antigen-like and opsin-like immunoreactions occur in nine of 28 medulloblastomas investigated. All tumors displaying S-antigen-like immunoreactive neoplastic cells also contain opsin-like immunoreactive cells; however, the opsin-like immunoreactive cells were less frequent than the S-antigen-like immunoreactive cells throughout all positive cases. The immunoreactive cells displayed several long processes. Generally, both S-antigen and opsin-like immunoreactive cells considerably vary in number among individual tumors. The results indicate that certain neoplastic cells of medulloblastoma are capable of expression of photoreceptor-specific proteins and, thus, may be closely related to tumor cells of retinoblastoma and pineocytomas previously shown to bind antisera against retinal S-antigen and opsin. No S-antigen and opsin-like immunoreaction was found in malignant teratomas and germinomas of the pineal gland, oat cell tumors, astrocytomas, ependymomas, oligodendrogliomas, glioblastomas, gangliogliomas, gangliocytoma, ganglioneuroblastomas, neuroblastomas, and esthesioneuroblastoma.