Malignant change in a benign eccrine spiradenoma is rare. Only 13 such cases have been previously reported. Two further cases are described herein, both of which were carcinosarcomas and arose in middle-aged women. In each case continuity was demonstrated between the benign and malignant epithelial components and the sarcomatous element. In case 1 the sarcomatous component showed osteocartilaginous and rhabdomyoblastic differentiation, whereas in case 2 only osteosarcoma was evident. To our knowledge, carcinosarcoma has not been previously described arising in eccrine spiradenoma. The literature regarding malignant eccrine spiradenoma is reviewed.