Malignant peripheral neuroectodermal tumours of childhood and adolescence.

Seventeen cases of malignant peripheral neuroectodermal tumour (MPNT) were studied by means of light microscopy, immunohistochemistry and electron microscopy. There were nine males and eight females. The mean age of the 17 patients was 10 years with a range of seven months to 20 years. The vast majority of tumours was located in the trunk. Histologically, they closely resembled Ewing's sarcoma, although minor differences were obvious. Special findings included ganglion cells and Flexner rosettes. In 10/11 cases positive staining for neuron-specific enolase (NSE) was obtained. Five of 10 tumours were positive for protein S-100. Three contained vimentin, two neurofilaments and one vimentin, neurofilaments and GFAP. Neurosecretory granules were noted in the three cases studied. Five patients died, three are alive with disease and five patients are alive without evidence of disease. It is concluded that these tumours form a homogeneous group, although the grade of differentiation varies. The prognosis in most cases is poor. Distinction from Ewing's sarcoma is possible by staining for NSE and by electron microscopy.