[An immunohistochemical study of retinoblastoma].

Various immunohistochemical marders were detected in 27 specimens of human retinoblastoma by the avidin-biotin-peroxidase complex technique, using mono- and polyclonal antibodies. The glial markers, glial fibrillary acidic protein and Leu-7 were detected in the retinal tissue component and reactive perivascular glial cells in the tumor mass. In only 4 of the 27 specimens, Leu-7 was positive in the glial cells randomly interspersed among the tumor cells and not associated with blood vessels. The neuronal marker, neuron-specific enolase, stained strongly positive in undifferentiated tumor cells in most (21/27) of the specimens. Rhodopsin, the photoreceptor marker which exists only in the outer segments of photoreceptor cells, was detected in the fleurettes of 1 tumor and in the rosettes of 6 tumors, these results support the view that retinoblastoma is chiefly neuronal in nature with tendency to differentiate into photoreceptor cells and rarely into glial cells.