Sellar/suprasellar extraventricular neurocytoma

Objective To explore the clinicopathological features of extraventricular neurocytoma located in the sellar/suprasellar region.  Methods The clinical manifestations, neuroimaging, histopathological, immunohistochemical and molecular genetic features were retrospectively analyzed in one case of sellar/suprasellar extraventricular neurocytoma, and the related literatures were reviewed.  Results A 27-year-old female presented with intermittent headache, accompanied by blurred vision for 5 months. Head MRI demonstrated a mass with a well-defined margin measuring 3.80 cm × 2.50 cm × 3.40 cm located in the sellar/suprasellar region. The tumor showed isointense to hyperintense signals on T 1 WI and hyper-hypointense mixed signals on T 2 WI, and slightly hyperintense signal on diffusion-weighted imaging (DWI). The pituitary was not shown. A transsphenoidal sellar tumor resection, cerebrospinal fluid (CSF) rhinorrhea repairing and optic decompression were performed. The mass was lightly yellow and tough with abundant blood supply and filled with old hemorrhage. The pituitary tissue was pushed to the left rear. Microscopy examination showed a diffuse invasive growth pattern with neuropil background in some area. The tumor cells were uniform on size and shape with round to oval, exquisite and hyperchromatic nuclei. No mitosis was found. Immunohistochemical staining showed the tumor cells were positive for neuronal nuclei (NeuN) and thyroid transcription factor-1 (TTF-1) in nuclei, calretinin (CR) in nuclei and cytoplasm, synaptophysin (Syn), chromogranin A (CgA), E-cadherin, matrix metalloproteinase-9 (MMP-9) in cytoplasm, and focally positive for S-100 protein (S-100) in nuclei, and neurofilament protein (NF), cytokeratin 8 (CK8) and vimentin (Vim) in cytoplasm. The Ki-67 labeling index was about 3%. The tumor tissue was negative for reticular fiber staining. Molecular genetic analysis showed that isocitrate dehydrogenasel (IDH) gene was not mutated, and 1p/19q was intact in tumor cells. The final pathological diagnosis was extraventricular neurocytoma, WHO grade Ⅱ.  Conclusions Extraventricular neurocytoma located in the sellar/suprasellar region is very rare. The histological features are similar to central neurocytoma in ventricle. Tumor cells were in diffusely invasive growth and were uniform in size and shape, with round nuclei. Fibrillary areas mimicking neurophil and branching thin-walled capillaries can be seen. The differential diagnosis includes pituitary adenoma, oligodendroglioma, clear cell ependymoma, and so on. DOI: 10.3969/j.issn.1672-6731.2017.12.009