Pathologic Study of Primitive Neuroectodermal Tumor: Report of 5 cases

ABSTRACT

Primitive neuroectodermal tumor (PNET) occuring in the brain (especially in the cereburm) of young individuals is a rare and highly malignant neoplasm. The authors analyzed 5 cases of primitive neuroectodermal tumor, operated from January 1986 to September 1987. They had characteristic clinical, radiologic and pathologic features. Patient's age ranged from 2 years to 14 years old (mean 8.2 years old) and there were 3 boys and 2 girls. They were rapidly growing tumor, with a brief duration of symptoms taking a rapidly progessive course. Computerized tomographic findings were characteristic, revealing the large, irregular, typically iso-to hyper-dense mass lesions with calcification and cystic or necrotic areas, and showing dense heterogeneous contrast enhancement of the mass in the cerebral hemisphere. Grossly all of the 5 cases showed hemorrhage and necrosis with sharp border and 2 cases showed calcification and cystic change grossly. Microscopically, they were predominantly composed of undifferentiated small dark cells with evidence of focal differentiation along glial and or neuronal lines. Four cases showed glial differentiation and three cases showed neuronal differentiation. Mesenchymal components were predominant in 3 cases.