title: Case of the month. May 1996--hydrocephalus in a 9 month old infant.
abstract: A 9 month old infant presented with hydrocephalus. MRI studies revealed a large cystic space with a nodule that was bright on T-1 weighted images and dark on T-2 weighted images. It was bright with contrast enhancement. The surgical specimen was noted to be dark black. Microscopic examination revealed a benign papillary tumor consistent with a choroid plexus papilloma which was heavily pigmented with melanin. Immunohisto-chemical stains were consistent with a choroid plexus papilloma, but they also showed many epithelial cells to be positive for HMB-45. Ultrastructural studies demonstrated melanosomes and pre-melanosomes in cells with well-delineated basal lamina. This is the first case to demonstrate melanosomes in a benign choroid plexus papilloma. Previously reported cases of pigmented lesions of the choroid plexus either contained neuromelanin in the benign examples or melanosomes in two cases of choroid plexus carcinomas.
authors.affiliation: Pathology Department, University of Pittsburgh, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Hamilton
mesh_terms: D016545:Choroid Plexus Neoplasms / Q000175:diagnosis / Q000473:pathology* / Q000648:ultrastructure; D004848:Epithelium / Q000473:pathology / Q000648:ultrastructure; D006801:Humans; D006849:Hydrocephalus / Q000209:etiology* / Q000473:pathology; D007223:Infant; D008279:Magnetic Resonance Imaging; D008544:Melanocytes / Q000473:pathology / Q000648:ultrastructure; D008854:Microscopy, Electron; D009419:Nerve Tissue Proteins / Q000032:analysis; D010212:Papilloma / Q000175:diagnosis / Q000473:pathology* / Q000648:ultrastructure
chemical_list: D009419:Nerve Tissue Proteins