title: Biphasic response of a tecto-mesencephalic pilocytic astrocytoma after Gamma Knife surgery--A case report.
abstract: Biphasic response (shrinkage-regrowth-shrinkage) of tumors has never previously been reported in the postoperative course, neither after microsurgery, nor after Gamma Knife surgery (GKS). We present the case of an adult with dorsal midbrain syndrome resulting from a pilocytic astrocytoma centered on the mesencephalic tectum. The tumor extended to the third ventricle and the thalamus. Initially, due to tumor growth, a biopsy was performed and histology established. Later, a ventriculocisternostomy for obstructive hydrocephalus was performed. Finally, GKS was performed, as the tumor continued to grow. After GKS, the lesion exhibited a biphasic response, with a major shrinkage at 3 months, regrowth within the target volume at 6 and 9 months and a second phase of important shrinkage at 12 months, which persisted for the next two years. The possible mechanisms for this particular response pattern are discussed.
authors.affiliation: Neurosurgery service, Gamma Knife center, CHU Vaudois, Lausanne, Switzerland; Medical image analysis laboratory (MIAL), CHU Vaudois, Lausanne, Switzerland; École politechnique fédérale de Lausanne, signal processing laboratory (LTS 5), Lausanne, Switzerland; Faculty of biology and medicine, university of Lausanne, Lausanne, Switzerland. Electronic address: constantin.tuleasca@gmail.com.
authors.forename: C
authors.initials: C
authors.lastname: Tuleasca
authors.affiliation: Radiation oncology service, CHU Vaudois, Lausanne, Switzerland; Radiation oncology department, Clinica Luganese, Lugano, Switzerland.
authors.forename: L
authors.initials: L
authors.lastname: Negretti
authors.affiliation: Institute of radiation physics, CHU Vaudois, Lausanne, Switzerland; Faculty of biology and medicine, university of Lausanne, Lausanne, Switzerland.
authors.forename: V
authors.initials: V
authors.lastname: Magaddino
authors.affiliation: Radiology department, CHU Vaudois, Lausanne, Switzerland; Faculty of biology and medicine, university of Lausanne, Lausanne, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Maeder
authors.affiliation: Neuropathology department, CHU Vaudois, Lausanne, Switzerland; Faculty of biology and medicine, university of Lausanne, Lausanne, Switzerland.
authors.forename: B
authors.initials: B
authors.lastname: Lhermitte
authors.affiliation: Unité de neuro-ophtalmologie, service universitaire d'ophtalmologie, hôpital ophtalmique Jules-Gonin, Lausanne, Switzerland; Faculty of biology and medicine, university of Lausanne, Lausanne, Switzerland.
authors.forename: F-X
authors.initials: FX
authors.lastname: Borruat
authors.affiliation: Neurosurgery service, Gamma Knife center, CHU Vaudois, Lausanne, Switzerland; Faculty of biology and medicine, university of Lausanne, Lausanne, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Levivier
mesh_terms: D001254:Astrocytoma / Q000175:diagnosis / Q000601:surgery*; D020295:Brain Stem Neoplasms / Q000175:diagnosis / Q000601:surgery*; D006801:Humans; D006849:Hydrocephalus / Q000175:diagnosis / Q000601:surgery*; D008297:Male; D008866:Microsurgery / Q000379:methods; D008875:Middle Aged; D016634:Radiosurgery / Q000379:methods; D013788:Thalamus / Q000601:surgery*; D014696:Ventriculostomy / Q000379:methods
keywords: Astrocytome pilocytique; Biphasic response; Gamma Knife surgery; Pilocytic astrocytoma; Radiochirurgie Gamma Knife; Réponse biphasique