Anaplastic evolution of childhood optico-hypothalamic pilocytic astrocytoma: report of an autopsy case.

A 19-month-old boy was found to have an optico-hypothalamic tumor with obstructive hydrocephalus, and received a ventriculoperitoneal (V-P) shunt followed by irradiation to the hypothalamic area. Although his visual disturbances continued, general conditions improved subsequently and he enjoyed normal life with only a visual disturbance. Four years later, however, he developed vomiting, left hemiparesis and dysuria, and died at the age of 6.5 years. Autopsy revealed a huge tumor occupying the hypothalamus, thalamus, basal ganglia and the right temporal lobe. Histologically, the tumor was composed of pilocytic astrocytes with Rosenthal fiber in the hypothalamus, where the tumor is considered to have developed initially, and poorly differentiated cells with some astrocytic and neuronal differentiation in other areas. Dissemination of the tumor was extensive in the whole CSF spaces, and in the peritoneum through the V-P shunt. We consider this a rare case of a childhood hypothalamic pilocytic astrocytoma undergoing delayed malignant evolution.