Fibro-Osseous Lesions of the Craniofacial Bones: β-Catenin Immunohistochemical Analysis and CTNNB1 and APC Mutation Analysis

The canonical Wnt/β-catenin pathway is involved in the formation of craniofacial skeleton and oral tissues. Aberrant nuclear localization of β-catenin protein has been described in several human diseases including a subset of odontogenic tumors thereby suggesting an important role in tumor developme...

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Published in:	Head & neck pathology (Totowa, N.J.) N.J.), 2014, Vol.8 (3), p.291-297
Main Authors:	E Horvai, Andrew, C Jordan, Richard
Format:	Article
Language:	eng
Subjects:	Adolescent Adult Aged beta Catenin - genetics Bone Diseases - genetics Bone Diseases - metabolism Bone Diseases - pathology Child Child, Preschool Dentistry DNA Mutational Analysis Facial Bones - pathology Female Genes, APC Humans Male Medicine Medicine & Public Health Middle Aged Mutation Oral and Maxillofacial Surgery Original Paper Otorhinolaryngology Pathology Reverse Transcriptase Polymerase Chain Reaction Skull - pathology Young Adult
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Summary:	The canonical Wnt/β-catenin pathway is involved in the formation of craniofacial skeleton and oral tissues. Aberrant nuclear localization of β-catenin protein has been described in several human diseases including a subset of odontogenic tumors thereby suggesting an important role in tumor development. Fibro-osseous lesions of the craniofacial skeleton comprise several neoplastic, and reactive mesenchymal proliferations in which β-catenin status is unknown. To study this, we immunostained 171 fibro-osseous lesions for β-catenin protein and, for lesions with nuclear positivity, sequenced exon 3 of the CTNNB1 gene and exon 15 of the APC gene. Nuclear β-catenin immunostaining was detected in 34 (20 %) tumors with no correlation between nuclear positivity and either age, gender, or tissue decalcification status ( p = 0.2, 0.17, 0.12, respectively). Absent nuclear β-catenin in fibrous dysplasia was the only diagnostically significant finding ( p = 0.0034). A single point mutation at Asp56 of CTNNB1 was identified in one case of ossifying fibroma. A second ossifying fibroma and one desmoplastic fibroma demonstrated point mutations (Glu1229 and Tyr1475, respectively) in the APC gene. These findings show that apart from fibrous dysplasia where nuclear β-catenin is rare, nuclear β-catenin staining has limited utility in discriminating among the craniofacial fibro-osseous lesions. The molecular mechanisms underlying nuclear β-catenin accumulation in the positive tumors is unlikely to be mediated by CTNNB1 exon 3 or APC exon 15 mutations in most cases.
ISSN:	1936-055X 1936-0568