title: Pilocytic astrocytoma presenting with atypical features on magnetic resonance imaging.
abstract: Pilocytic astrocytoma, which is classified as a grade I astrocytic tumor by the World Health Organization, is the most common type of glioma in children and young adults. Pilocytic astrocytoma generally appears as a well-circumscribed, contrast-enhancing lesion, frequently with cystic components on magnetic resonance imaging (MRI). However, it has been reported that the MRI appearance of pilocytic astrocytoma may be similar to that of high-grade gliomas in some cases. We here report on 6 cases of pilocytic astrocytoma with atypical MRI findings, including small cyst formation, heterogeneously enhancing tumor nodules, irregularly enhancing tumor nodules, and enhancing tumor nodules with internal hemorrhage. All tumors were successfully resected, and the histological diagnoses were pilocytic astrocytoma. When the tumor is located near a cerebral cistern or ventricle, the risk of leptomeningeal dissemination is increased. Furthermore, partial resection has also been associated with a higher risk of recurrence and leptomeningeal dissemination. To date, all but one patient are alive and recurrence-free. Because the preoperative diagnosis influences the decision on the extent of resection and because of the high risk of leptomeningeal dissemination associated with these tumors, careful and correct diagnosis by MRI is important.
authors.affiliation: Department of Neurosurgery, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, 807-8555 Kitakyushu, Japan. Electronic address: yo-naka@med.uoeh-u.ac.jp.
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Nakano
authors.affiliation: Department of Neurosurgery, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, 807-8555 Kitakyushu, Japan.
authors.forename: Junkoh
authors.initials: J
authors.lastname: Yamamoto
authors.affiliation: Department of Neurosurgery, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, 807-8555 Kitakyushu, Japan.
authors.forename: Mayu
authors.initials: M
authors.lastname: Takahashi
authors.affiliation: Department of Neurosurgery, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, 807-8555 Kitakyushu, Japan.
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Soejima
authors.affiliation: Department of Neurosurgery, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, 807-8555 Kitakyushu, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Akiba
authors.affiliation: Department of Neurosurgery, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, 807-8555 Kitakyushu, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Kitagawa
authors.affiliation: Department of Neurosurgery, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, 807-8555 Kitakyushu, Japan.
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Ueta
authors.affiliation: Department of Neurosurgery, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, 807-8555 Kitakyushu, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Miyaoka
authors.affiliation: Department of Neurosurgery, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, 807-8555 Kitakyushu, Japan.
authors.forename: Takeru
authors.initials: T
authors.lastname: Umemura
authors.affiliation: Department of Neurosurgery, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishiku, 807-8555 Kitakyushu, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Nishizawa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000473:pathology*; D001921:Brain / Q000473:pathology*; D001932:Brain Neoplasms / Q000473:pathology*; D003937:Diagnosis, Differential; D003951:Diagnostic Errors / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*
keywords: Glioma; Magnetic resonance imaging; Pilocytic astrocytoma