Primary melanoma over epidermoid cyst. A rare tumoral association

We present a case of epidermoid cyst located in fronto-temporal area in a 69 years old patient with comitial crisis of 40 years evolution and cerebral ictus. The patient developed, over the cyst wall, a malignant tumor identified morphollogically and immunohistochemically, with aid of HMB-45 monoclonal antibody, as a malignant melanoma. The lack of records the propper characteristics and the sistemic radiologic study of this lesion, lead to consider a diagnostic of primary malignant melanoma over a epidermoid cyst, discussing the histogenesis of this possible association.