Hemangioblastoma is the most common benign, primary intrinsic tumor of the posterior fossa in adults and has also been referred to as hemangioma, capillary hemangioendothelioma, Lindau tumor, and angioreticuloma.

Hughlings Jackson described the first case, a cerebellar cyst with an angiomatous tumor in the cyst wall, in 1872. Von Hippel described retinal hemangioblastoma in 1904. Lindau recognized the association of retinal, visceral and cerebellar components of Von Hippel-Lindau (VHL) disease in1926. In 1928, Cushing & Bailey called it hemangioblastoma which is widely accepted.

Epidemiology:

They consitute1% of primary intracranial tumors and 7-12% of posterior fossa tumors. They may occur sporadically or in about 20-30% of cases as a part of VHL complex which belongs to a group of disorders known as phakomatoses or neurocutaneous syndromes. 50% of patients with VHL complex have CNS hemangioblastoma. VHL complex is a familial disorder which has an autosomal inheritance with variable penetrance and can be passed on by the affected and the unaffected members. VHL complex is characterized by single or multiple hemanigioblastomas in the neuroaxis associated with one or more of the following: retinal hemangioblastoma, renal carcinoma, renal cysts, pancreatic cysts,cysts and angiomas of the liver, epididymal cysts and adenomata and phaeochromocytoma. Familial occurrence of solitary hemangioblastoma has been reported without any stigmata of VHL disease. There is an association between this disease and rearrangements involving human chromosome 3p, most commonly deletion mutations at 3p25-p26, dubbes the VHL gene. 

The commonest age at presentation is between the third and fourth decades with a male preponderance, and younger in VHL complex.  

They may occur concurrently with other intracranial meningioma and acoustic neuroma or AVM. Supratentorial locations are rare (about 2-8% of all hemangioblastomas) and are usually soild. They constitute 2% of spinal neoplasms, usually thoracic or cervical. 60% of them are intramedullary, with associated syrinx.

Pathology: 

It is almost exclusively a lesion of the cerebellum (85%). Spinal cord (3%) is the next common site. Rarely, a hemangioblastoma develops in the medulla oblongata (mainly in VHL) either as a solitary lesion or in association with a similar cerebellar tumor. Multiple tumors occur only in VHL. The tumor is benign but local recurrence occurs with incomplete removal.  Metastases are exceptional.   

It is a benign, slowly growing, highly vascular lesion (usually supplied from pia) of uncertain histogenesis (WHO Grade I).   

It is generally believed that they arise from angiogenic cell precursors.

On immunohistochemistry, the  stromal cells may label with S100, vimentin or even GFAP (which may suggest a heterogeneous origin for the stromal cells is probably due to the stromal cells taking up extracellular GFAP protein derived from adjacent reactive astrocytes), but do not stain with EMA or cytokeratins.

Clinical features:

There are no signs and symptoms specific for hemangioblastoma.

Posterior fossa lesions usually present with signs of raised ICT with headache (44%), deteriorating conscious level (84-93%), neck stiffness due to tonsilar impaction (9%), and pappiledema (70%). 18% of them present with dementia due to insidious hydrocephalus. Associated cerebellar signs may be there.

Supratentorial lesions usually present with focal neurological signs and symptoms depending upon site.

Rarely, they may present as SAH or ICH.

Another rarer presentation is with secondary polycythemia as tumor can produce erythropoietin.

Spinal lesions may present with signs of spinal cord compression or syrinx. 

Investigations: 

Blood Count may reveal secondary polycythemia due to erythropoietin production by the tumor occurs in up to 50% of cases, usually in solid tumors and not in association with spinal lesions. There is neither splenomegaly nor an increase in WBCs or platelets. The stromal cell component is responsible for erythropoietic hormone.

Polycythemia improves on tumor removal and returns with tumor recurrence and may help as a tumor marker during follow ups.

AVM and astrocytoma may mimic spinal hemangioblastoma. 

Angiogram may demonstrate mural nodule as a vascular mass.  Multiple small nodular lesions can be visualized.  Spinal angiogram demonstrates tumor nodule and vascular supply. 

Treatment: 

Surgical removal of the mural nodule and drainage of the cyst through a appropriate approach is curative.  Cyst drainage alone is of no benefit.  However, solid tumors, including spinal lesions tend to be highly vascular.

They should not be biopsied,  but an attempt should be made to remove en masse as for an AVM. 

Brainstem hemangioblstomas also tend to be solid and highly vascular and partial removal only may be possible. The problems in surgery include risk to the cardio-respiratory system because these tumors frequently are adherent to the floor of the fourth ventricle which is close to the cardio-respiratory control center.

A peroperative CSF drainage in associated hydrocephalus helps; A shunt, as a first stage, is recommended by some.

Preoperative embolisation may be of benefit. 

The location of the tumor is suggested by dilated pial vessels, especially in solid lesions. Use of an endoscope or stereotactic craniotomy will help in localizing a small mural nodule which may be missed in conventional techniques.

Radiotherapy (approx. 50 Gy) may reduce tumor size and vascularity, but does not prevent regrowth. It is useful in poor surgical candidates, and technically difficult cases.

The place of stereotactic radiosurgery for tumors extending into the brainstem is yet to be evaluated. 

Outcome: 

Most series include pre-CT and ‘pre-microsurgery’ cases, so estimates of morbidity and mortality may vary. This will depend upon the site of the tumor, its nature (cystic or solid), multiplicity and association with VHL. 

Good outlook with complete excision of cystic tumor since always benign (90% 5 year survival).  With incomplete removal of solid, vascular tumor, operative mortality can be high (15%) with 50% mortality from tumor recurrence in survivors.

In VHL, the survival may depend upon systemic lesions (>25% develop renal adenocarcinoma).  Recurrence rate of 3-10% even after total excision has been reported. However recurrence may represent a second primary.  Repeated surgeries should be considered. It is recommended that patient's family should be screened regularly.