Palisading pattern in cerebral neuroblastoma mimicking the primitive polar spongioblastoma. An ultrastructural study.

The present case study portrays a neoplasm composed predominantly of palisading uni- and bipolar cells with histological features mimicking the polar spongioblastoma. Ultrastructural examination of this single case reveals cells that range from the embryonal neuroepithelial cell to neurons with synapse formation and the presence of dense-cored vesicles in neurites. The morphology of these neoplastic cells is similar to the neuronal line of differentiation described in both normal developing mammalian central nervous system and in the transplantable mouse teratoma line (OTT-6050). Glial differentiation is not present in the areas of palisading. We would like to emphasize that the diagnostic pattern characteristic of the polar spongioblastoma may be found in tumors of neuronal origin, although most polar spongioblastomas having the typical pattern of palisading seem to belong to the astrocytic cell line.