Minichromosome maintenance proteins are useful adjuncts to differentiate between benign and malignant melanocytic skin lesions.

BACKGROUND: Markers identifying premalignant and malignant melanocytic skin lesions are needed.

OBJECTIVE: We aimed to investigate the protein expression of minichromosome maintenance (MCM) proteins in melanocytic skin lesions with different malignant potential.

METHODS: Paraffin-embedded sections of benign melanocytic nevi (BN, n = 37), dysplastic nevi (DN, n = 25), and primary superficial spreading (SSM, n = 58) were assessed. Immunohistochemistry was performed for Ki-67, MCM3, MCM4, and MCM7 antibodies.

RESULTS: Ki-67 expression of SSM was significantly increased when compared to DN (P = .0001) and BN (P = .0015). Compared to BN and DN, expression of MCM3 was significantly increased in SSM (P < .0001 and P = .019, respectively). MCM3 expression of DN was significantly increased as compared to BN (P = .0067). There was a significant correlation between MCM3 expression and Breslow tumor thickness (r = 0.44, P = .019). In SSM, MCM4 expression was significantly increased when compared with DN (P < .0001) and BN (P = .0033). MCM4 immunoreactivity was significantly higher in DN than in BN (P = .016). Immunohistology of MCM7 did not reveal significant differences between the groups investigated (P = .48). However, immunoreactivity of MCM7 significantly correlated with Breslow tumor thickness and Clark level (r = 0.39, P = .023; r = 0.44, P = .010, respectively).

LIMITATIONS: Limitations of our study include the absence of survival data, mRNA results, and functional studies.

CONCLUSIONS: MCM3 as well as MCM4 are differentially expressed in BN, DN, and SSM. Hence, immunolabeling of MCM3 and MCM4 proteins appears to be a promising additive tool for distinguishing benign from malignant melanocytic skin lesions.