Survey of the karyotype of 90 human retinoblastomas, with emphasis on changes in chromosomal regions known to contain oncogenes and tumor suppressor genes. The data support the hypothesis that retinoblastoma occurs after multiple and often varied steps, similar to other human malignancies. Histologic examination of sections of the eye showed a retinal tumor that was centered in the equatorial region and had the typical features of a poorly differentiated retinoblastoma. Focal choroidal invasion and seeding of the anterior and posterior chambers were observed. Immunoreactivity of the tumor cells for neuron-specific enolase confirmed that the tumor is a neuronal neoplasm consistent with retinoblastoma.
Retinoblastoma occurring in adults is a rare finding.
In most large series of retinoblastomas, no adults are included. Only eight patients 20 years of age or older with retinoblastomas have been documented previously. In the current case, the patient had no evidence of orbital recurrence or metastasis 6 years after enucleation of the eye. It may be important for clinicians to consider this diagnosis when confronted with a retinal mass of unknown etiology in adults. This incidence may be an overestimate because of difficulties in distinguishing a second malignancy from recurrent tumor.