Dysembryoplastic neuroepithelial tumor-like neoplasm of the septum pellucidum: review of 2 cases with chromosome 1p/19q and IDH1 analysis.

Dysembryoplastic neuroepithelial tumor (DNT)-like neoplasms of the septum pellucidum are extremely rare. We reviewed 2 cases of DNT-like neoplasm of the septum pellucidum and specifically studied the immunohistochemical features and chromosomes 1p and 19q deletions. One case was a 26-year-old woman who complained of aggravated headache for 2 weeks. The other case was a 31-year-old female presenting with double vision for a month. Histological examinations showed that the lesions were composed of uniform oligodendrocytelike cells (OLCs) with obvious floating neurons in a mucin-rich background. Immunohistochemical studies revealed that both tumors were diffusely positive for Synaptophysin and Olig2. Sporadic neurons were clearly positive for NeuN. Loss of chromosome 1p/19q and isocitrate dehydrogenase 1(IDH1) mutations were not identified in both cases. It might indicate that these OLCs of DNT-like neoplasms were genetically different from glial tumors, although they showed close morphological similarities.