Trilateral retinoblastoma: bilateral retinoblastoma with pinealoblastoma

Bilateral retinoblastoma was diagnosed in a 12-month-old boy. The left eye was enucleated; the choroid and the optic nerve were not invaded by the tumour. The right eye had three lesions: one was photocoagulated, and the other two were irradiated. Two years later, symptoms and signs of intracranial hypertension prompted computerized tomography, which demonstrated a mass in the pineal region and secondary hydrocephalus. The right eye showed papilledema but no evidence of tumour activity in the three retinal scars. Radiation therapy and chemotherapy had only a transient effect, and the child died at 42 months of age. At autopsy the pineal region and the third ventricle were found to be replaced by a pinealoblastoma with retinomatous differentiation. Only 11 other cases of pinealoblastoma associated with bilateral (heritable) retinoblastoma have been reported. The embryologic relationship between the pineal gland and the retina has given rise to the concept of trilateral retinoblastoma, a concept important in the investigation and follow-up of patients with bilateral retinoblastoma.