Malignant transformation of a benign cutaneous mixed tumour.

Whilst benign cutaneous mixed tumour is common, malignant cutaneous mixed tumour is rare. There are only eleven accepted cases of the malignant counterpart in the literature. In none was there residual benign tumour tissue present to suggest that they arose from malignant transformation of the benign tumour. We report a very rare case of a malignant transformation of a benign cutaneous mixed tumour in an eighty-four year old female. Other unusual features in this case included considerable involvement of bone in the primary lesion and the histological picture of extreme pleomorphism and active mitoses, not seen in other reported cases of the malignant tumour.