title: Pilocytic Astrocytoma Enlargement Following Irradiation: Relapse or Pseudoprogression?
abstract: Pilocytic astrocytomas are the most common gliomas (World Health Organization (WHO) grade 1) in children. According to many authors, stereotactic irradiation (radiotherapy and radiosurgery) is an effective method that provides a prolonged, recurrence-free survival in patients who have had partial tumor removal or in patients with an unresectable tumor. We present a case of a patient with midbrain pilocytic astrocytoma that enlarged considerably in the first six months after irradiation and then diminished in size during the next six months without any antitumor treatment. The clinical and radiological follow-up data for this patient, the surgery results for similar patients, and the data from other authors led us to the conclusion that early tumor volume enlargement after irradiation is usually pseudoprogression.
authors.affiliation: Radiology and Radiosurgery, Burdenko Neurosurgery Institute.
authors.forename: Yury
authors.initials: Y
authors.lastname: Trunin
authors.affiliation: Department of Radiation Oncology, Burdenko Neurosurgery Institute.
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Golanov
authors.affiliation: Gamma Knife, Neurosurgery Business Center.
authors.forename: Valery V
authors.initials: VV
authors.lastname: Kostjuchenko
authors.affiliation: Department of Radiation Oncology, Burdenko Neurosurgical Institute.
authors.forename: Mikhail
authors.initials: M
authors.lastname: Galkin
authors.affiliation: Burdenko Neurosurgery Institute.
authors.forename: Alexander N
authors.initials: AN
authors.lastname: Konovalov
keywords: irradiation; pilocytic astrocytoma; pseudoprogression; radiotherapy