Background:Mucosal melanomas in the head and neck region are most frequently located in the nasal cavity and paranasal sinuses. Sinonasal mucosal melanoma (SNMM) comprises <1% of all melanomas. The aim was to determine the KIT, NRAS and BRAF mutation frequencies in a large series of primary SNMMs.Methods:Laser capture microdissection was used to isolate tumour cells from 56 formalin-fixed paraffin-embedded tumours. The tumour cells were screened for KIT, NRAS and BRAF mutations by direct sequencing.Results:Overall, 21% (12 out of 56) of SNMMs harboured KIT, NRAS or BRAF mutations. Mutations in these oncogenes occurred in a mutually exclusive manner. Both KIT and BRAF mutations were identified at a similar frequency of 4% each (2 out of 56), whereas NRAS mutations were detected in 14% (8 out of 56) of the SNMMs. Four of the NRAS mutations were located in exon 1. Mutations in these oncogenes were significantly more common in melanomas located in the paranasal sinuses than in nasal cavity (P=0.045). In a multivariate analysis, patients with melanomas in the nasal cavity had a significantly better overall survival than those with tumours in the paranasal sinuses (P=0.027).Conclusion:Our findings show that KIT and BRAF mutations, which are accessible for present targeted therapies, are only rarely present in SNMMs, whereas NRAS mutations seem to be relatively more frequent. The data show that majority of SNMMs harbour alterations in genes other than KIT, NRAS and BRAF.
We found VE1 immunohistochemical analysis to be a useful and rapid assay for BRAFV600E mutations that may contribute to the detection of intratumoral and intertumoral heterogenetic subclones. Tumors with positive results, including strong staining, should be expedited for confirmatory BRAF mutation testing. If this test result is negative, a false-negative result of the mutation analysis should be considered. Validation of VE1 immunohistochemical analysis in clinical practice is needed.
Sinonasal malignant melanoma (SNMM) comprises less than 1% of all melanomas and is located in the nasal cavity and the paranasal sinuses. The majority of SNMMs have unknown underlying oncogenic driver mutations. The recent identification of a high frequency of driver mutations in the promoter of the telomerase reverse transcriptase (TERT) gene in cutaneous melanoma led us to investigate whether these mutations also occur in SNMM. Our aim was to determine the TERT promoter mutation frequencies in primary SNMMs. Laser capture microdissection and manual dissection were used to isolate tumour cells from 49 formalin-fixed paraffin-embedded tissues. The tumours were screened for TERT promoter mutations by direct Sanger sequencing. Information on NRAS, BRAF and KIT mutation was available from an earlier study. Overall, 8% (4/49) of SNMMs harboured TERT promoter mutations. One of these mutated tumours had a coexistent NRAS mutation and one had a BRAF mutation. Our findings show that TERT promoter mutations are present in a moderate proportion of SNMM. No conclusion can be drawn on their potential influence on the clinical outcome or tumour progression.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.