MAGNETIC-RESONANCE-IMAGING AND PATHOLOGICAL ANALYSIS OF A PITUICYTOMA- CASE-REPORT

A CASE OF a pituicytoma is presented that describes the clinical, path ological, and magnetic resonance imaging features of a rare tumor of t he neurohypophysis. A 26-year-old woman presented with a 4-month histo ry of dizziness and visual obscuration. A magnetic resonance image rev ealed a pituitary mass with suprasellar extension. The specimen obtain ed from a transsphenoidal decompression identified the mass as an astr ocytoma of the posterior pituitary (pituicytoma). Immunohistochemical staining was positive for glial fibrillary acidic protein, S-100, and vimentin. Electron microscopy identified intermediate filaments, numer ous broad cell junctions, no secretory granules, and two cellular popu lations with either an electron-dense or lucent cytoplasmic matrix. Th is case is unique in that other documented cases originating in the po sterior pituitary have all been pilocytic astrocytomas, whereas this n eoplasm was not a pilocytic variant. This is also the first case in th e literature of a pituicytoma documented by magnetic resonance imaging . This report reviews the cytological elements of the neurohypophysis and the origin of pituicytomas and stresses the proper use of the term ''pituicytoma'' in relation to tumors of the posterior pituitary.