Neuron-specific Enolase in Retinoblastoma. An Immunohistochemical Study

Forty-six retinoblastoma specimens were studied for the presence of neuron-specific enolase (NSE) in the tumour cells and in the remaining morphologically normal retina. The laboratory method was a sensitive immunohistochemical peroxidase staining procedure, and normal ocular nerves were used as positive controls. Neuron-specific enolase was found in perikarya and cell processes in all layers of morphologically normal appearing neuroretina, but not in Müller's cells. All but two of the retinoblastomata studied contained positively staining tumour cells, whereas stromal cells remained constantly negative. Many Flexner-Wintersteiner rosettes stained positively as well. The proportion of retinoblastoma cells expressing neuron-specific enolase seemed to be greater in small tumours, in bilateral cases, and in tumours that contained rosettes. The presence of neuron-specific enolase in tumour cells seems to favour a neuronal or neuroectodermal origin for retinoblastoma, but it should be noted that this marker has recently been found in several non-neuronal and non-neuroectodermal malignant neoplasms.