We describe a case of an occipital lobe primitive neuroectodermal tumor (PNET) in a 60-year-old man with immunocytochemical evidence of neuronal, glial, smooth muscle and adipose tissue differentiation in the primary tumor and its metastases. This is the first case of PNET of cerebrum in which adipose tissue and smooth muscle has been demonstrated. The possible cells of origin for these mesenchymal elements is discussed.