Abstract In the following case report we describe a 66 year-old man who was presented with a squamous cell carcinoma (epithelial tumour) on the skull which grew on the scar of a previously surgically excised sarcoma (mesenchymal tumour). This is the first description of such a coincidence, which may be due to the development of a mutated stem cell colony, which differentiated in tumour cells of several lineages.