[Comparative study of HMB-45 monoclonal antibody uptake on various benign and malignant melanocytic lesions]

In order to evaluate a possible discriminatory diagnosis interest of HMB-45 monoclonal antibody in different melanocytic population, it was tested on 48 benign and malignant melanocytic lesions embedded in paraffin. There were made of 16 benign nevus (33%), 18 dysplastic nevus (38%) and 14 malignant melanomas (29%). The reaction was positive in 11 benign tumors (69%), 18 dysplastic nevus (100%), and 12 malignant melanomas (86%); negative in 5 dermal nevus (31%) and 2 desmoplastic melanomas (14%). We have researched, by the KHI square (chi 2) statistical test, a relation between the reaction intensity, its cutaneous location, and the tumor type. The reaction intensity is not statistically linked with the tumor type. The cutaneous location of the reaction is statistically more heterogeneous in malignant melanoma than in benign or dysplastic melanocytic lesions. Among the dysplastic nevus, 6 cases (38%), of the familial type, have an heterogeneous reaction looking like the malignant melanoma's one. However, there is no significant difference, in the reaction pattern, between dysplastic and benign lesions. Nevertheless some dysplastic nevus seems to have a phenotypic expression for HMB-45 midway between benign and malignant melanocytic lesion, that will be interesting to precise. Otherwise, the simple use and the staining of HMB-45 monoclonal antibody are of great interest to assess the depth of primary cutaneous melanoma and to diagnose secondary melanoma. However, the negativity of the spindle cell type justify the association of other markers, particularly the S100 protein, which is more sensitive, in the diagnosis of desmoplastic malignant melanoma.