Cerebellar hemangioblastoma is a vascular posterior fossa tumor with a clear border that develops intramedullary to extramedullary.
Histologically 1) and radiologically 2) , cerebellar HBs are traditionally described as four types:
Type 1 (5% of posterior fossa HBs) is a simple cyst without a macroscopic nodule.
Type 2 is a cyst with a mural nodule (60%).
Type 3, or solid tumors (26%).
Type 4, or solid tumors with small internal cysts (9%), are also seen in the cerebellum and predominate in the spinal cord.
Some authors have stated that type 1 is actually rare.
Several primary pathologic entities in diverse anatomic locations have the potential to simulate metastatic neoplasms histologically. Their misinterpretation as such may result in needless and extensive clinical evaluations that are intended to detect a presumed malignancy at another site. More importantly, mistakes of this type can deprive patients of surgical excisions that could be curative 3).
In adults with only cerebellar masses, cerebellar hemangioblastoma and cerebellar metastases are the 2 most important differential diagnoses.
High b value DWI reflects diffusion more accurately than does regular b value. Results showed that ADC calculation by high b value (b = 4000) DWI at 3-T magnetic resonance imaging is clinically useful for differentiating hemangioblastomas from brain metastases 4).
Arterial spin labelled imaging can aid in distinguishing hemangioblastoma from metastasis in patients with only cerebellar masses 5).
Coexistence of hemangioblastomas and AVMs is extremely rare, and only 3 cases have been reported previously in the literature 6).
Effectiveness is dubious. May be useful to reduce tumor size or to retard growth, e.g. in patients who are not surgical candidates, for multiple small deep lesions, or for inoperable brainstem HGB. Does not prevent regrowth following subtotal excision.
Gamma Knife Radiosurgery as well as LINAC have also been employed to successfully treat recurrence and control tumor growth of cerebellar hemangioblastomas.
A retrospective chart review revealed 12 patients with a total of 20 intracranial hemangioblastomas treated with GKRS from May 1998 until December 2014. Kaplan-Meier plots were used to calculate the actuarial local tumor control rates and rate of recurrence following GKRS. Univariate analysis, including log rank test and Wilcoxon test were used on the Kaplan-Meier plots to evaluate the predictors of tumor progression. Two-tailed p value of <0.05 was considered as significant. Median follow-up was 64months (2-184). Median tumor volume pre-GKRS was 946mm3 (79-15970), while median tumor volume post-GKRS was 356mm3 (30-5404). Complications were seen in two patients. Tumor control rates were 100% at 1year, 90% at 3years, and 85% at 5years, using the Kaplan-Meier method. There were no statistically significant univariate predictors of progression identified, although there was a trend towards successful tumor control in solid tumors (p=0.07). GKRS is an effective and safe option for treating intracranial hemangioblastoma with favorable tumor control rates 7).
Suzuki et al. emphasize the usefulness of embolization with N-butyl cyanoacrylate for hemangioblastoma with ruptured feeder aneurysm, by which the aneurysm and the feeder could be simultaneously embolized 8).
Surgical treatment may be curative in cases of sporadic HGB, not in VHL.
Solitary hemangioblastomas are for the most part considered benign, curable by total resection, except in those cases associated with von Hippel Lindau disease.
Despite extensive literature describing the diagnosis, treatment, and prognosis of these lesions, 9) individual cases still present a surgical quandary given their frequently eloquent location and high degree of vascularity.
Bründl et al. retrospectively analyzed the clinical, radiological, surgical, and histopathologic records of 24 consecutive patients (11 men, 13 women; mean age 51.3 years) with HBL of the posterior cranial fossa, who had been treated between 2001 and 2012.
Mean time to diagnosis was 14 weeks. The extent of resection (EOR) was total in 20 and near total in 4 patients. Four patients required revision within 24 h because of relevant postoperative bleeding. One patient died within 14 days. One patient required permanent shunting. At discharge, 75% of patients [n = 18, modified Rankin scale (mRS) 0-1] showed no or at least resolved symptoms. Mean follow-up was 21 months. Two recurrences were detected during follow-up.
In comparison to other benign entities of the posterior fossa, time to diagnosis was significantly shorter for HBL. This finding indicates the rather aggressive biological behavior of these excessively vascularized tumors. In this series, however, the rate of complete resection was high, and morbidity and mortality rates were within the reported range 10).
Cerebrospinal fluid dissemination of cerebellar hemangioblastoma was found dominantly in non-Von Hippel Lindau disease patients. The diagnosis was made 10 years after the initial surgery. Irradiation therapy was performed, but the patients died about 2 years after the diagnosis was given. Molecular targeted therapies including vascular proliferation suppression have been attempted lately, but no effective therapy has been established. Early diagnosis of dissemination as well as combination of aggressive excision and stereotactic radiosurgery are considered to be appropriate for current interventions 11).