title: A case of clear cell meningioma with tyrosine-rich crystals.
abstract: We present a case of clear cell meningioma with unusual clinical and pathologic features. The patient was a 54-year-old man who underwent laminectomy and durotomy for an intradural tumor in the lumbar spinal canal. Sections showed a predominance of dense collagenous tissue with irregularly shaped and irregularly sized magenta-colored extracellular deposits. On electron microscopy, these deposits were osmiophilic and "petaloid." The final diagnosis of clear cell meningioma rested on relatively inconspicuous intervening nests of glycogen-containing clear cells that were positive for epithelial membrane antigen. The unusual extracellular deposits seen in this case have previously been characterized as tyrosine-rich crystals of the type most commonly seen in salivary gland tumors. Recognition of this tumor as a clear cell meningioma, despite misleading clinical features and initially challenging histologic findings, is not only a matter of diagnostic accuracy but also imparts important prognostic information.
authors.affiliation: Dalhousie University, Halifax, Nova Scotia, Canada. erica.schollenberg@cdha.nshealth.ca
authors.forename: Erica
authors.initials: E
authors.lastname: Schollenberg
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Easton
mesh_terms: D003460:Crystallization; D006801:Humans; D002479:Inclusion Bodies / Q000648:ultrastructure*; D008297:Male; D008577:Meningeal Neoplasms / Q000648:ultrastructure*; D008579:Meningioma / Q000648:ultrastructure*; D008875:Middle Aged; D014443:Tyrosine
chemical_list: D014443:Tyrosine