Primary Intracranial Germ Cell Tumor Originating From Septum Pellucidum That Mimics Central Neurocytoma Intracranial germ cell tumors (GCTs), representing 2% to 3% of primary intracranial tumors, are rare neoplasms affecting children and young adults. 1 GCTs of various histological types mainly occur in the pineal (48%) and suprasellar (neurohypophyseal) regions (37%). 2,3 Even though GCTs harbor predominately in these midline sites within the CNS, 3 the basal ganglia, 4-7 thalamus, 7-9 cerebellar vermis, 10 ventricular system 11 and optic chiasm 12 are other atypical sites from which GCTs can arise. Here, we present an extremely rare case of a primary intracranial germinoma originating from septum pellucidum with radiological find- ings that mimic central neurocytoma (CN). To the best of our knowledge, this is the first ever reported case of primary intracranial germinoma of septum pellucidum. Moreover, the novelty of this case report is that along with the challenge of differential diagnosis between GCT of septum pellucidum and CN preoperatively, we review previous four cases 13-17 of intracranial GCTs in septum pellucidum. Case Report A 24-year-old female patient who suffered a seizure and headache 2 months previously was admitted to the hospital with a seizure-like movement. On initial brain magnetic resonance (MR) imaging, the 5-cm–sized heterogeneously enhancing mass in septum pellucidum with a suspected focal extension into the left side of corpus callosal genu portion was detected (Figs 1A and 1B). No abnormal findings in both pineal and suprasellar regions were detected. With suspected CN, a left frontal craniotomy and tumor removal via a frontal transcortical approach were planned. During operation, the mass in the left lateral ventricle was friable, gray-colored and highly vascularized. Since the frozen biopsy result was GCT, not CN, the surgeon discontinued the operation and performed only a biopsy. Contrary to the initial preoperative diagnosis, histological diagnosis of the main mass in septum pellucidum was germinoma. Moreover, only a diffused expression of c-Kit was found, and placental alkaline phos- phatase, CD30, alpha feto-protein (AFP) and beta human chorionic gonadotropin (-hCG) were not expressed (Figs 2A and 2B; H & E, hematoxylin and eosin). Endocrine studies showed within normal range of tumor marker levels, AFP serum level (2.9 ng/mL) and -hCG serum level ( 1.20 mU/mL). The whole-body positron emis- sion tomography scan revealed no abnormal findings. After establishing the histological diagnosis, the patient first re- ceived two cycles of chemotherapy using bleomycin, etoposide, and cisplatin followed by radiation therapy, 19.8 Gy to the ventricular system and 16.2 Gy to the tumor bed (total, 36 Gy). The most recent B A Fig 1. JOURNAL OF CLINICAL ONCOLOGY DIAGNOSIS IN ONCOLOGY VOLUME 30  NUMBER 27  SEPTEMBER 20 2012 e274 © 2012 by American Society of Clinical Oncology Journal of Clinical Oncology, Vol 30, No 27 (September 20), 2012: pp e274-e277 Downloaded from jco.ascopubs.org on June 18, 2016. For personal use only. No other uses without permission. Copyright © 2012 American Society of Clinical Oncology. All rights reserved.