We present here ultrastructural findings in three composite tumours having giant cell fibroblastoma--dermatofibrosarcoma protuberans components occurring in adult patients. We further hypothesize that these 3 tumours belong to the group of neoplasms that can show giant cell fibroblastoma, dermatofibrosarcoma protuberans, dendritic pigment cell, myxoid, and fibrosarcomatous differentiation. We consider the giant cell fibroblastoma areas of the tumours to represent a well-differentiated component of these neoplasms.