Comparing the differential expression patterns of CD9 with distant metastasis status and considering that all patients affected by thin melanomas showed no evidence of disease progression, it was found that 29 of the 45 primary intermediate and thick melanomas with distant metastasis (64%) were stained for CD9 (CD9+M1) while only 15 CD9 positive patients had no metastasis (CD9+M0) (p < 0.001). Here, CD9 is linked to melanoma.