HMB45 - A SPECIFIC MARKER FOR MELANOMA METASTASES IN THE CENTRAL-NERVOUS-SYSTEM

The monoclonal antibody HMB45 is used to detect an epitope specific fo r melanocytes, malignant melanomas and melanoma metastases. Using the PAP method, we observed consistent expression of HMB45 in 19 metastase s of melanotic and amelanotic malignant melanomas of the central nervo us system, while metastases of 32 adenocarcinomas, 10 squamous cell an d 8 small cell carcinomas were negative except for 2 cases of breast c ancer. Differential diagnosis between cancer and melanoma metastases c an be made using cytokeratins as an additional immunocytochemical mark er protein. Ten meningeomas and 5 pineocytomas were also negative. Eve n though it is not absolutely specific, we consider the HMB45 immunore action diagnostic for a metastasis of a malignant melanoma if the tumo ur is cytokeratin negative and HMB45 positive in a large number of tum our cells.