Merlin expression in secretory meningiomas: evidence of an NF2-independent pathogenesis? Immunohistochemical study.
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.
Buccoliero
Anna Maria
AM
Department of Human Pathology, University of Florence, Italy. ambuccoliero@unifi.it
Gheri
Chiara Francesca
CF
Castiglione
Francesca
F
Ammannati
Franco
F
Gallina
Pasquale
P
Taddei
Antonio
A
Garbini
Francesca
F
Rossi Degl'Innocenti
Duccio
D
Arganini
Luisa
L
Di Lorenzo
Nicola
N
Mennonna
Pasquale
P
Taddei
Gian Luigi
GL
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*
D025581:Neurofibromin 2