High concordance of BRAF mutational status in matched primary and metastatic melanoma

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Cormican, David
Kennedy, Ciaran
Murphy, Sandra
Werner, Reiltin
Power, Derek G.
Heffron, Cynthia C. B. B.
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Background: Techniques for the accurate identification of activating mutations of BRAF in metastatic melanoma are of great clinical importance, due to the availability of targeted therapies for these tumours. There is uncertainty regarding the frequency with which BRAF status differs between primary and metastatic sites. Methods: Between 2011 and 2016, 219 melanoma cases underwent BRAF testing in our institution. In 53 of these, paired primary and metastatic specimens were available for PCR and immunohistochemical evaluation. Results: 52 out of 53 cases (98%) showed concordant BRAF status between primary and metastatic site by IHC. In one case, a metastasis and its matched primary were positive by IHC but the metastasis was negative on PCR. On further investigation, PCR was positive in the primary and repeat PCR in the metastasis was positive, following macrodissection. Conclusions: Our results suggest that discordance of BRAF mutational status between primaries and metastases is a rare occurrence. In one case, immunohistochemistry provided strong evidence that initial PCR testing had provided a false negative result due to low tumour volume. Thus, in cases where tissue is difficult to obtain from a metastasis or unavailable, the primary tumour can be used with confidence.
Melanoma , BRAF , Immunohistochemistry , Metastasis
Cormican, D., Kennedy, C., Murphy, S., Werner, R., Power, D. G. and Heffron, C. C. (2018) 'High Concordance of BRAF Mutational Status in Matched Primary and Metastatic Melanoma', Journal of Cutaneous Pathology, In Press, doi: 10.1111/cup.13393
© 2018 John Wiley & Sons, Inc. All rights reserved. This is the peer reviewed version of the following article: Cormican, D. , Kennedy, C. , Murphy, S. , Werner, R. , Power, D. G. and Heffron, C. C. (2018), High Concordance of BRAF Mutational Status in Matched Primary and Metastatic Melanoma. J Cutan Pathol. Accepted Author Manuscript, which has been published in final form at https://doi.org/10.1111/cup.13393. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.