CADHERIN EXPRESSION IN MELANOCYTIC NEVI AND MALIGNANT MELANOMAS

An immunocytochemical study has been undertaken of cadherin expression in 11 benign melanocytic naevi and 14 malignant melanomas. Anti-pan-c adherin 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 melano cytes which possessed abundant cytoplasm (type A melanocytes). More de eply located melanocytes possessing little cytoplasm (type B melanocyt es) or having a spindle cell morphology (type C melanocytes) lacked de tectable pan-cadherin expression. The monoclonal antibody HECD-1 detec ted weak E-cadherin immunostaining in all 11 naevi, expression again b eing limited, with a single exception, to type A melanocytes. Cadherin immunostaining of moderate or strong intensity was detected by the pa n-cadherin antibody in all 14 malignant melanomas. In contrast to naev i, cadherin expression in melanomas frequently extended into the deepe st portions of the tumours. E-cadherin immunostaining in malignant mel anomas was generally much stronger than that seen in naevi, often bein g of comparable intensity to the pan-cadherin staining. In summary, ca dherins are frequently expressed in melanocytic tumours. In naevi, cad herin expression is related to the degree of melanocytic maturation. C adherin expression, and particularly E-cadherin expression, tends to b e greater in malignant melanomas than in naevi.