MAY 1996 - HYDROCEPHALUS IN A 9 MONTH OLD INFANT

A 9 month old infant presented with hydrocephalus, MRI studies reveale d a large cystic space with a nodule that was bright on T-1 weighted i mages and dark on T-2 weighted images. It was bright with contrast enh ancement. The surgical specimen was noted to be dark black, Microscopi c examination revealed a benign papillary tumor consistent with a chor oid plexus papilloma which was heavily pigmented with melanin, immunoh istochemical stains were consistent with a choroid plexus papilloma, b ut they also showed many epithelial cells to be positive for HMB-45. U ltrastructural studies demonstrated melanosomes and pre-melanosomes in cells with well-delineated basal lamina, This is the first case to de monstrate melanosomes in a benign choroid plexus papilloma. Previously reported cases of pigmented lesions of the choroid plexus either cont ained neuromelanin in the benign examples or melanosomes in two cases of choroid plexus carcinomas.