Cadherin Expression in Melanocytic Naevi and Malignant Melanomas

An immunocytochemical study has been undertaken of cadherin expression in 11 benign melanocytic naevi and 14 malignant melanomas. Anti-pan-cadherin rabbit antibodies, which recognize multiple cadherin subtypes, demonstrated cadherin expression of moderate or strong intensity in 8 of 11 naevi. Expression was restricted to the more superficial melanocytes which possessed abundant cytoplasm (type A melanocytes). More deeply located melanocytes possessing little cytoplasm (type B melanocytes) or having a spindle cell morphology (type C melanocytes) lacked detectable pan-cadherin expression. The monoclonal antibody HECD-1 detected weak E-cadherin immunostaining in all 11 naevi, expression again being limited, with a single exception, to type A melanocytes. Cadherin immunostaining of moderate or strong intensity was detected by the pan-cadherin antibody in all 14 malignant melanomas. In contrast to naevi, cadherin expression in melanomas frequently extended into the deepest portions of the tumours. E-cadherin immunostaining in malignant melanomas was generally much stronger than that seen in naevi, often being of comparable intensity to the pan-cadherin staining. In summary, cadherins are frequently expressed in melanocytic tumours. In naevi, cadherin expression is related to the degree of melanocytic maturation. Cadherin expression, and particularly E-cadherin expression, tends to be greater in malignant melanomas than in naevi.