Contribution of MRI in the diagnosis of haemangioblastomas

Management Strategies and Outcomes for VHL-related Craniospinal Hemangioblastomas

Hemangioblastomas are rare and benign tumors accounting for less than 2% of all central nervous system (CNS) tumors. The vast majority of hemangioblastomas occur sporadically, whereas a small number of cases, especially in younger patients, are associated with Von Hippel–Lindau (VHL) syndrome. It is thought that loss of tumor suppressor function of the VHL gene results in stabilization of hypoxia-inducible factor alpha with downstream activation of cellular proliferative and angiogenic genes that promote tumorigenesis. VHL-related hemangioblastomas predominantly occur in the cerebellum and spine. Lesions are often diagnosed on contrast-enhanced craniospinal MRIs, and the diagnosis of VHL occurs through assessment for germline VHL mutations. Surgical resection remains the primary treatment modality for symptomatic or worrisome lesions, with excellent local control rates and neurological outcomes. Stereotactic radiotherapy can be employed in patients who are deemed high risk for surgery, have multiple lesions, or have non-resectable lesions. Given the tendency for development of either new or multiple lesions, close radiographic surveillance is often recommended for asymptomatic lesions.

A rational approach to radiological screening in von Hippel-Lindau disease

OBJECTIVES

To optimise radiological screening in von Hippel-Lindau disease (VHL) while minimising cost and morbidity.

METHODS

A model of VHL was based on retrospective studies, and Bayes's theorem used to calculate the probability of the gene's presence and the likelihood of further lesions in affected families. A six year follow up was conducted to test the validity of the model.

RESULTS

Follow up confirmed the accuracy and validity of the model. Posterior fossa haemangioblastomas occur in 79.2% of VHL cases, supratentorial, retinal and spinal haemangioblastomas in 6.9%, 42.8%, and 22.0%, phaeochromocytomas in 5.2%, and renal carcinomas in 14.5%. Population incidences are 1:15,700 live births (posterior fossa), 1:780,000 (supratentorial), and 1:116,000 (spinal). The birth rate of subjects with VHL is 1:43,000; new mutations occur in 1:178,000 live births. Penetrance is 90%; 40% present with multiple lesions and 6.4% die within two years after diagnosis.

CONCLUSIONS

For most patients presenting with a VHL-type lesion, with sufficient clinical and pedigree data, the presence or absence of the VHL gene, and the probability of further lesions occurring, can be assessed with a high degree of accuracy using the method described in this paper. Those cases in the non-VHL group do not require long term radiological follow up, nor do their relatives require radiological screening. Subjects in the VHL group should be screened for renal carcinoma indefinitely from the age of 20 years, and all clinically unaffected relatives should be screened genetically for the VHL gene. (Those found negative for the gene do not require further screening, but those found positive should be screened.)

MR findings of posterior fossa hemangioblastomas

MR findings of five posterior fossa hemangioblastomas were reported. In the cystic type, a cyst was low intensity on T1WI and high intensity on T2WI. Mural nodule was clearly enhanced by Gd-DTPA. In the solid type, the tumor was shown as an isointense lesion on T1WI and as high intensity on T2WI, but it was markedly and homogeneously enhanced by Gd-DTPA. Multiple extremely low-intensity serpentine "flow void" signs, indicating afferent and efferent vessels, were observed within or around the tumor. These were characteristic pictures in this tumor.

Use of gadolinium-enhanced magnetic resonance imaging in the diagnosis and management of posterior fossa hemangioblastomas

The diagnosis of central nervous system hemangioblastoma as well as the surgical treatment requires the accurate radiologic visualization of both the cystic and solid components of the tumor. We report two cases of posterior fossa hemangioblastoma examined with gadolinium-diethylenetriaminepentaacetic acid-enhanced magnetic resonance imaging, which clearly defined the tumor nodule that was not visualized on noncontrast magnetic resonance imaging, contrast-enhanced computed tomography scans, or angiography. In both cases the operative findings precisely correlated with the gadolinium-enhanced magnetic resonance image. Gadolinium-enhanced magnetic resonance imaging is the examination of choice for preoperative evaluation of posterior fossa hemangioblastoma. In cases of von Hippel-Lindau syndrome, magnetic resonance imaging is a useful tool for clinical screening as well as follow-up.

Intramedullary vascular lesions in the high cervical region: transoral and dorsal surgical approach. Two case reports

Intramedullary vascular malformations in the high cervical region are extremely rare. Two young adult patients with vascular lesions at the level C 2 and 3, and C 2-4 are reported. In one patient selective spinal angiography revealed a combined malformation with a ventral intramedullary arteriovenous angioma and a premedullary aneurysm. This malformation was approached and removed transorally after spondylectomy of C 2. In the second patient MRI and selective angiography showed an intramedullary hemangioblastoma extending from C 2-C 4. After embolization, this lesion was surgically removed via a dorsal approach. Both patients suffered from severe neurological deficits preoperatively. MRI and selective angiography showed the exact locations of the tumors within the spinal cord and indicated a transoral approach in one case and a dorsal approach in the other. After complete obliteration and removal of the lesions, the patients showed no neurological deficits and returned to their previous professions.