BRAF and mucosal melanoma: All melanoma of unknown primary origin harbored a BRAF alteration (100%, 4/4 samples), whereas an alteration of BRAF gene was recorded in 40.4 % (38/94) of cutaneous melanomas, 28.6% (2/7) of acral melanomas and in 11.1% (1/9) of the mucosal melanomas.