title: Merlin expression in secretory meningiomas: evidence of an NF2-independent pathogenesis? Immunohistochemical study.
abstract: One of the most common chromosomal regions implicated in the meningiomas tumorigenesis is 22q12 where the neurofibromatosis 2 (NF2) gene resides. The NF2 tumor-suppressor gene encodes for the merlin/schwannomin protein, which is responsible for the inherited disease neurofibromatosis 2. NF2 gene mutations predominantly occur in transitional and fibroblastic meningiomas, whereas the meningothelial variant is less affected. Secretory meningioma is an infrequent meningioma subtype. Its most typical morphologic feature is the presence of intracytoplasmic or extracytoplasmic round hyaline, eosinophilic, and periodic acid Shiff-positive bodies in a lesion frequently otherwise classifiable as meningothelial meningioma. This study reviews the immunohistochemical merlin expression in 14 consecutive secretory meningiomas. Our purpose was to investigate if secretory meningiomas, analogous to meningothelial meningiomas, follow a molecular route of pathogenesis independent of the neurorofibromatosis 2 gene-associated pathway. All meningiomas showed positive immunocoloration involving the majority of the hyaline inclusions and secretory cells; in 12 (86%) meningiomas, a positive immunoreaction was also documented in nonsecretory tumoral cells. Our results may indicate a molecular, besides morphologic, similarity between secretory and meningothelial meningiomas: the almost constant merlin immunohistochemical expression in our series gives evidence for a possible NF2 gene-independent pathogenesis in secretory meningiomas.
authors.affiliation: Department of Human Pathology, University of Florence, Italy. ambuccoliero@unifi.it
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Buccoliero
authors.forename: Chiara Francesca
authors.initials: CF
authors.lastname: Gheri
authors.forename: Francesca
authors.initials: F
authors.lastname: Castiglione
authors.forename: Franco
authors.initials: F
authors.lastname: Ammannati
authors.forename: Pasquale
authors.initials: P
authors.lastname: Gallina
authors.forename: Antonio
authors.initials: A
authors.lastname: Taddei
authors.forename: Francesca
authors.initials: F
authors.lastname: Garbini
authors.forename: Duccio
authors.initials: D
authors.lastname: Rossi Degl'Innocenti
authors.forename: Luisa
authors.initials: L
authors.lastname: Arganini
authors.forename: Nicola
authors.initials: N
authors.lastname: Di Lorenzo
authors.forename: Pasquale
authors.initials: P
authors.lastname: Mennonna
authors.forename: Gian Luigi
authors.initials: GL
authors.lastname: Taddei
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008577:Meningeal Neoplasms / Q000209:etiology* / Q000235:genetics / Q000473:pathology; D008579:Meningioma / Q000209:etiology* / Q000235:genetics / Q000473:pathology; D008875:Middle Aged; D025581:Neurofibromin 2 / Q000032:analysis / Q000235:genetics / Q000378:metabolism*
chemical_list: D025581:Neurofibromin 2