Chapter 28
Hemangioblastoma: Stereotactic Radiosurgery Anand Veeravagu, Bowen Jiang, and Steven D. Chang
Abstract CNS hemangioblastomas are rare, vascular neoplasms that arise primarily in the posterior cranial fossa. Prognosis is generally favorable, with a recurrence rate of fewer than 25% in multiple surgical series. Although current standard of care for CNS hemangioblastomas is surgical resection, other treatment modalities including endovascular embolization and stereotactic radiosurgery (CyberKnife, LINAC, Gamma Knife) are being applied. Increasing evidence has suggested the effectiveness of stereotactic radiosurgery in managing CNS hemangioblastomas. Herewithin, we review the indications and multiinstitutional experiences in using such a treatment modality. Keywords Radiosurgery · Hemangioblastomas · Tumor
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Introduction Central nervous system (CNS) hemangioblastomas were first described in the cerebellum by Jackson in 1872. Hemangioblastomas are usually slow growing tumors which account for 1–3% of all CNS neoplasms and 7–10% of posterior fossa tumors. These highly vascular and histologically benign (WHO I) lesions consist of a small mural nodule with an
S.D. Chang () Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA 94305-5484, USA e-mail:
[email protected]
associated pseudocyst in 30–80% of cases, with the remaining lesions consisting of solid tumors. The tumor tissue itself has a well defined border and has a bright red color on gross morphological examination (Fig. 28.1). Histologically, hemangioblastomas are vascular lesions containing channels lined by cuboidal epithelium and are interspersed with nests of foamy stromal cells and pericytes. Mast cells are also found and may be responsible for the production of erythropoietin which can cause erythrocytosis (Fig. 28.2). Although debate still exists, the clusters of stromal cells surrounding the vascular plexus are thought to be the neoplastic component of the lesions. These lesions typically occur in the cerebellum (63%), spinal cord (32%), and brainstem (5%), though some cases of lumbosacral nerve root and supratentorial lesions have been reported as well. There is not thought to be any sex or ethnic predominance and the mean age at diagnosis is in the late third or early fourth decade of life. CNS hemangioblastomas are most commonly treated by surgical resection, which is an effective strategy capable of achieving curative results. A number of large clinical case series have shown that when appropriately applied, surgical resection is often necessary to provide symptomatic improvement. In the case of unfavorable anatomic location or post surgical recurrence, radiosurgery is often the next line of treatment. In particular, our experience and the reported literature surrounding the use of stereotactic radiosurgery (CyberKnife, LINAC, Gamma Knife) highlight favorable outcomes in certain clinical settings. The size, morphology, location, and clinical presentation of hemangioblastomas must all be considered when choosing treatment.
M.A. Hayat (ed.), Tumors of the Central Nervous System, Volume 5, DOI 10.1007/978-94-007-2019-0_28, © Springer Science+Business Media B.V. 2012
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Fig. 28.1 Histologic Appearance of hemangioblastoma. (a) low power (100×; H&E): well-demarcated proliferation of vessels and stromal cells with adjacent gliosis (b) medium power
(200×; H&): capillary network and admixed stromal cells (c) higher power (400×; H&E): vacuolated stromal cells and fine capillaries
Fig. 28.2 MRI with Gadolinium enhancement at T1/T2/FLAIR weightings. (a) Axial T1-weight post contrast images showing recurrent cerebellar hemangioblastoma associated with a large, cystic cavity. (b) Coronal T1-weight post contrast images again
demonstrating focus of recurrent hemangioblastoma and associate cystic cavity. (c) Axial T1-weight post contrast images demonstrating interval resection of mural nodule and drainage of associated cerebellar cyst with decompression of posterior fossa
Conventional Radiotherapy
a high dose of radiation. One study of 24 patients noted a 10-year survival rate of 57% for patients treated with more than 36 Gy, compared with a survival rate of 27% for patients treated with less than 36 Gy. In another review of 27 patients irradiated postoperatively (19 with gross residual disease and 6 with VHL disease), local control was achieved for 33% of patients treated with less than 50 Gy, compared with 57% of those who received more than 50 Gy. Although conventionally fractionated irradiation seems to increase the probability of hemangioblastoma control, local control even with increased radiation doses is less than optimal. Furthermore, the exposure to significant volumes of normal tissue with radiotherapy remains a concern.
Radiosurgical treatment of hemangioblastomas has become increasingly popular. Current indications for radiosurgery for hemangioblastomas include: 1) Unfavorable and inaccessible region of the CNS axis, 2) Recurrence after surgical resection (particularly in VHL patients), 3) Medical co-morbidities that preclude surgery. As with other radiosurgical targets, hemangioblastomas treated with radiosurgery are typically less than 3 cm in size. Contraindications to radiosurgery for hemangioblastomas include tumors greater than 3 cm and those inducing significant neurologic symptoms due to mass effect and edema requiring urgent decompression. The rationale for radiosurgery for hemangioblastomas comes from prior use of conventionally fractionated external beam radiation for residual or unresectable hemangioblastomas. Studies suggest that control of hemangioblastomas depends upon achieving
Stereotactic Radiosurgery Because single fractions of 20–25 Gy have been estimated to achieve the biological equivalence of 50–100 Gy administered by conventional fractionated
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irradiation, stereotactic radiosurgery may provide better control than that achieved with standard radiotherapy, especially for highly vascular, benign tumors. The steep dose gradient achieved with this technique minimizes damage to eloquent structures in the posterior fossa. Because hemangioblastomas are typically small, well-defined tumors that show no histological infiltration, they are ideally suited for radiosurgical treatment. In a recent study from the NIH, 20 patients with 44 lesions were treated with Gamma Knife SRS. At a mean follow-up of 8.5 years (range 3.0–17.6 years), all 20 patients remained living. Local control was reported to be 91, 83, and 61% at 2, 5, and 10 years after Gamma Knife SRS, respectively (Asthagiri et al., 2010). This group noted that 33% of SRS treated asymptomatic, small (
