Retinoblastoma and intracranial malignancy.

The occurrence of independent brain tumors in two patients with retinoblastoma is described. One patient with well-differentiated biliteral retinoblastomas developed, over two years later, a pineal tumor but no other metastatic lesions. The pineal tumor was composed of small neuroblastic cells and a second population of larger cells with vesicular nuclei and more abundant cytoplasm. This feature is not characteristic of either primary or metastatic retinoblastoma. In the second patient the symptoms of a brain tumor led to the discovery of a small uniocular, well-differentiated retinoblastoma. The brain tumor was retrochiasmal, highly differentiated (showing areas of photoreceptor differentiation), and interpreted as an ectopic nonmetastatic retinoblastoma. The possible histogenetic origins of the brain tumors are discussed. Patients who develop symptoms of a brain tumor after a prolonged interval since the treatment of their ocular tumors should be suspected of harboring a second intracranial primary.