Conflicts of interest None declared.
BRAF V600E mutation and the tumour suppressor IGFBP7 in atypical genital naevi
Article first published online: 16 NOV 2009
© 2009 The Authors. Journal Compilation © 2009 British Association of Dermatologists
British Journal of Dermatology
Volume 162, Issue 3, pages 677–680, March 2010
How to Cite
Nguyen, L.P., Emley, A., Wajapeyee, N., Green, M.R. and Mahalingam, M. (2010), BRAF V600E mutation and the tumour suppressor IGFBP7 in atypical genital naevi. British Journal of Dermatology, 162: 677–680. doi: 10.1111/j.1365-2133.2009.09558.x
- Issue published online: 15 FEB 2010
- Article first published online: 16 NOV 2009
- Accepted for publication 21 September 2009
- atypical genital naevi;
- BRAF V600E;
Background Atypical genital naevi (AGN) are naevi of special sites with atypical histological features that overlap with those of malignant melanoma. Activating BRAF mutations, identified in the majority of banal melanocytic naevi and cutaneous melanomas, are reportedly uncommon in naevomelanocytic proliferations in nonsun-exposed sites. We have recently shown that constitutive activation of the BRAF-MEK-ERK signalling pathway in oncogenic BRAF-positive naevi increases expression and secretion of IGFBP7, which induces senescence and apoptosis.
Objectives To ascertain the frequency of BRAF V600E mutations in AGN compared with banal naevi without atypia. An additional aim was to assess the expression of IGFBP7 in oncogenic BRAF-positive AGN.
Methods Genomic DNA was isolated per protocol from seven genital naevi without atypia and 13 AGN for BRAF genotyping. Immunohistochemical staining for IGFBP7 was performed on all cases.
Results The BRAF V600E mutation was identified in 43% of genital naevi without atypia and 23% of AGN (P = 0·61). In both groups, IGFBP7 expression was maintained in 67% of BRAF V600E-positive cases.
Conclusions The prevalence of BRAF V600E in AGN suggests that ultraviolet exposure is not essential for generating the mutation. The BRAF V600E mutational status appears to be of limited diagnostic utility in distinguishing genital naevi that exhibit atypia from those that do not. Similar to oncogenic BRAF-positive common naevi without atypia, enhanced expression of the tumour suppressor IGFBP7 in oncogenic BRAF-positive AGN supports that they are biologically inert.