A 71-year-old woman presented with the symptoms of a posterior cranial foss
a mass. CT and MRI revealed a lytic lesion in the occipital bone and tumour
infiltrating the dura mater, venous sinuses and cerebellum. Histopathology
demonstrated a moderately differentiated squamous cell carcinoma arising f
rom a primarily intradiploic epidermoid cyst. Despite surgery and radiother
apy, the tumour progressed and the patient died 1 year later.