Dysembryoplastic neuroepithelial tumor - Features distinguishing it from oligodendroglioma on cytologic squash preparations

OBJECTIVE: To evaluate the diagnostic usefulness of intraoperative cytologic preparations from dysembryoplastic neuroepithelial tumor (DNTs). STUDY DESIGN: We reviewed squash preparations from 17 DNTs and compared them to those from 12 oligodendrogliomas and the histology of frozen sections from the same tumors. RESULTS: The floating neurons and extracellular mucin typical of DNT were more easily demonstrated in cytologic preparations than in frozen sections. Cytologically, oligodendroglialike cells of DNT were distinguished from oligodendrogliomas by larger nuclei with frequent nuclear indentation and multiple, small nucleoli, while oligodendrogliomas consistently showed nuclear roundness of tumor cells with I or 2 occasional nuclei. The presence of eosinophilic granular bodies in the background was an ancillary sign of DNT. CONCLUSION: The cytologic features of squash preparations of DNT are fairly characteristic and reliable for the correct intraoperative diagnosis of DNT, helping to determine the appropriate neurosurgical procedure.