Hemangioblastoma

Background:

• Hemangioblastomas are made up of neoplastic stromal cells and an extensive vascular network. They usually occur in the cerebellum, brainstem, or spinal cord, and are associated with Von Hippel-Lindau syndrome. About 75 percent of cases are sporadic.

Clinical Presentation:

• The clinical presentation is not specific. Hemangioblastomas can cause symptoms relating to compression of neural structures, bleeding, or paraneoplastic complications (polycythemia due to erythropoietin production).

Key Diagnostic Features:

• MRI : Typically (60% of cases), hemangioblastomas are sharply demarcated homogeneous masses composed of a cyst with nonenhancing walls, except for a mural nodule that is T1 hypointense to isointense, T2 hyperintense, and vividly enhances. T2 flow voids due to enlarged vessels may be evident, especially at the periphery of the cyst, seen in 60–70% of cases. In the remaining 40%, the tumor is solid with no cystic cavity.

• Location: Predominantly within the posterior fossa, but supratentorial location along the optic pathway can also occur.

• Screening of the entire neural axis is recommended to assess for other lesions, especially in the spine. Assessment for other tumors seen in the setting of VHL syndrome such as endolymphatic sac tumor.

Differential Diagnoses:

• Metastases: usually multiple, but the most common are parenchymal posterior fossa lesions in patients older than 40 years of age. Metastases can be very vascular, too. They are more commonly solid than cystic, as opposed to the solid-cystic nature of hemangioblastoma.
• Vestibular schwannoma: typical extension into the internal auditory canal. Usually these do not demonstrate such marked intrinsic vascularity.
• Cerebellopontine angle meningioma: sessile, broadly based, homogeneously enhancing lesion along the petrous ridge, reflecting its dural attachment.    

Treatment:

• Surgical treatment is recommended for symptomatic lesions or those increasing in size on imaging. Preoperative embolization can be required for large, deep, or highly vascularized lesions.