Clinicopathological analysis of 12 cases with extraventricular neurocytoma / 临床与实验病理学杂志

Purpose To study the clinicopathological features of extraventricular neurocytoma. Methods 12 cases of extraventricular neurocytoma were retrospectively analyzed for their clinical information and histopathological features. Results The distribution of ex-traventricular neurocytoma was as follows: cerebral hemisphere (5 cases), right thalamus (2 cases), cerebellar vermis (2 cases), saddle area (2 cases), and spinal cord (1 case). The histological features were round uniform cells, round or oval nuclei, with peri-nuclear clearing commonly seen. Neuropil-like structure, ganglion cells or ganglion-like cells, perivascular rosettes, calcification, cap-illary wall thickening and hyaline degeneration and other pathological changes were also observed. All cases showed strong immunoreac-tivity for Syn. 7 cases exhibited Ki-67 labeling index of≤2%, and other 5 cases showed 3% ~8%. 3 cases were performed with fluo-rescence in situ hybridization ( FISH) to detect loss of chromosome 1p/19q, but no loss was detected. Postoperative follow-up for 4 months to 4 years showed one case had tumor recurrence and intracranial spread in postoperative 2 years. Conclusions Extraventricu-lar neurocytoma shares similar histological features with central neurocytoma, but often more complex. Ganglion cells or ganglion-like cells, calcification, capillary wall thickening and hyaline degeneration are more frequently seen, but neuropil-like structure is less seen. Extraventricular neurocytoma needs differential diagnoses from oligodendroglioma, ependymoma, dysembryoplastic neuroepitheli-al tumor and others. Immunohistochemistry and chromosome 1p/19q loss can help in the differential diagnosis. The treatment for ex-traventricular neurocytoma is grossly total resection, with post-operative radiotherapy for subtotal resection, atypical or recurrent cases.

5-Aminolevulinic Acid Fluorescence Discriminates the Histological Grade of Extraventricular Neurocytoma

Extraventricular neurocytomas are rare brain tumors that have a diverse range of clinical characteristics. We describe two cases involving fluorescence-guided resection of extraventricular neurocytoma using 5-aminolevulinic acid (5-ALA) and evaluate the efficacy of the technique. We found that the tumor reactions to 5-ALA differed depending on the histologic grade. This finding shows that the 5-ALA fluorescence reaction may potentially be used as a biomarker of the clinical behavior of these tumors. To our knowledge, this is the first report in which fluorescence-guided resection was utilized for the resection of extraventricular neurocytomas.

Atypical Extraventricular Neurocytoma

The authors report a case of atypical extraventricular neurocytoma (EVN) transformed from EVN which had been initially diagnosed as an oligodendroglioma 15 years ago. An 8-year-old boy underwent a surgical resection for a right frontal mass which was initially diagnosed as oligodendroglioma. When the tumor recurred 15 years later, a secondary operation was performed, followed by salvage gamma knife treatment. The recurrent tumor was diagnosed as an atypical EVN. The initial specimen was reviewed and immunohistochemistry revealed a strong positivity for synaptophysin. The diagnosis of the initial tumor was revised as an EVN. The patient maintained a stable disease state for 15 years after the first operation, and was followed up for one year without any complications or disease progression after the second operation. We diagnosed an atypical extraventricular neurocytoma transformed from EVN which had been initially diagnosed as an oligodendroglioma 15 years earlier. We emphasize that EVN should be included in the differential diagnosis of oligodendroglioma.

Recurrent Extraventricular Neurocytoma with Malignant Glial Differentiation

We present a case of recurrent extraventricular neurocytoma with malignant glial differentiation in left temporoparietal area. A 37-year-old man with presentation of generalized seizure had undergone biopsy of brain tumor in left parietal area in 1987, which revealed extraventricular neurocytoma and radiotherapy was followed. Postoperative course was uneventful until eleven years after biopsy, when he became gradually aphasic and right hemiplegic. Brain CT and MRI revealed enlargement of tumor with peritumoral edema and calcifications. He underwent subtotal tumor removal in 1998. Microscopic examination of second biopsy specimen revealed presence of large areas composed of anaplastic glial cells with frequent mitosis, nuclear pleomorphism, large eosinophilic cytoplasm and eccentric nuclei, resembling gemistocytes, which were strongly immunoreactive to glial fibrillary acidic protein(GFAP) but not to synaptophysin(SNP). Also focal areas of neuronal cells were found, which were immunoreactive to SNP but not to GFAP. These histologic findings imply that this recurred tumor was a high grade, mixed tumor with divergent differentiation of neuronal and astrocyte lineage. We report a rare case of extraventricular cerebral neurocytoma with malignant glial differentiation with review of the literature.