title: Delayed resolution of intracranial germinoma after radiotherapy: a preliminary study of the correlation between histology and magnetic resonance imaging.
abstract: A central nervous system germinoma is curable in most cases by radiotherapy, and most of the tumor mass disappears promptly after 20-30 doses. However, some germinomas take a longer period to vanish completely from magnetic resonance imaging (MRI) or computed tomography (CT) scans. In such cases, the tumor may contain components such as teratoma. The aim of this study was to clarify the nature of the persistence of some germinomas. Five cases of histologically verified germinoma in which radiotherapy was performed to treat residual tumor were selected. The doses of focal radiotherapy and whole brain radiotherapy were 10-20 Gy and 20-34 Gy, respectively. In these cases, correlation was made between the degree of persistence of the tumor when assessed by MRI and the amount of interstitial content, as determined by histology. The histological evaluation, using hematoxylin-eosin stain, silver impregnation and Azan staining was carried out independently of clinical information. The tumor vanished soon after radiotherapy in three cases, but 3-15 months passed before the tumor completely vanished from the MRI scans in the other two cases. The histology of the cases in which the tumor disappeared rapidly was predominantly of large tumor cells and only small amounts of reticulin. However, in the persistent tumors, large amounts of reticulin and vascular components were present. Thus, it is proposed that tumors with a large parenchymal component disappear soon after radiotherapy, whereas tumors composed mainly of interstitial component persist. Long-standing enhancement seen on MRI or CT scans of patients with an intracranial germinoma is indicative of a large amount of interstitial component in the tumor.
authors.affiliation: Department of Neurosurgery, Miyazaki Prefectural Hospital, Kiyotake, Japan. hochiai@fc.miyazaki-med.ac.jp
authors.forename: H
authors.initials: H
authors.lastname: Ochiai
authors.forename: Y
authors.initials: Y
authors.lastname: Yamakawa
authors.forename: T
authors.initials: T
authors.lastname: Fukushima
authors.forename: Y
authors.initials: Y
authors.lastname: Sato
authors.forename: T
authors.initials: T
authors.lastname: Hayashi
authors.forename: H
authors.initials: H
authors.lastname: Yamada
mesh_terms: D000293:Adolescent; D000328:Adult; D001932:Brain Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D002648:Child; D018237:Germinoma / Q000473:pathology* / Q000532:radiotherapy*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010870:Pineal Gland / Q000473:pathology* / Q000528:radiation effects*; D012189:Retrospective Studies; D013997:Time Factors; D017211:Treatment Failure