BACKGROUNDAlthough there were several clinical and experimental studies discussing the pathogenesis of dural arteriovenous fistula (DAVF), the pathological process leading to intracranial DAVF so far remains unknown. In this study, we investigated the expression of vascular growth factors in order to elucidate the possible role of these factors for the development of DAVF and to study the biological activity of this uncommon lesion.

METHODSWe examined the histological features, proliferative and angiogenic capacities of the tissue specimens obtained from 6 patients who underwent surgery at our institution. Immunohistochemical staining for vascular endothelial growth factor (VEGF), its receptors Flk-1 and Flt-1, ephrin-B2, MIB-1 and proliferating cell nuclear antigen (PCNA) was performed using standard immunohistochemical techniques.

RESULTSA positive immunostaining was found for all antibodies studied except MIB-1, whereas nuclear endothelial expression of PCNA was observed in only 3/6 cases. VEGF stained positive in all of the available specimens (6/6). Flk-1 showed a positive immunoreaction in only 2/6 cases and Flt-1 in 4/6 cases. Ephrin-B2 was expressed in the majority (5/6) of the cases.

CONCLUSIONSThese results support the hypothesis that DAVFs might be acquired dynamic vascular malformations with low biological activity. Vascular growth factors like VEGF and ephrin-B2 might play a pivotal role in the formation of DAVF.

Aged ; Cell Division ; Central Nervous System Vascular Malformations ; etiology ; metabolism ; pathology ; Endothelial Cells ; cytology ; Ephrin-B2 ; analysis ; physiology ; Female ; Humans ; Immunohistochemistry ; Ki-67 Antigen ; analysis ; Male ; Middle Aged ; Neovascularization, Physiologic ; Proliferating Cell Nuclear Antigen ; analysis ; Vascular Endothelial Growth Factor A ; analysis

BACKGROUNDSchwannoma is the tumor arising mainly from the cranial and spinal nerves. Bilateral vestibular schwannoma is the hallmark of neurofibromatosis type 2 (NF2). The NF2 gene has been cloned with comprehensive analysis of its mutations in schwannoma. However, most studies focused on vestibular schwannoma. There are differences in proliferation of tumor cell and ultrastructure between vestibular and spinal schwannomas. It is unknown whether genetic alterations in vestibular schwannoma are different from those in non-vestibular schwannoma. We analyzed the loss of heterozygosity (LOH) on chromosome 22 in patients with sporadic schwannoma including vestibular and spinal schwannomas and correlated this genetic alteration with tumor proliferation.

METHODSIn 54 unrelated patients without clinical NF1 or NF2, 36 patients had sporadic vestibular schwannoma, and 18 dorsal spinal root schwannoma. Four highly polymorphic linkage to NF2 gene microsatellite DNA markers (D22S264, D22S268, D22S280, CRYB2) were used to analyze LOH. The proliferative index was evaluated by Ki-67 and proliferative cell nuclear antigen (PCNA) immunostaining. Student's t test was used to analyze the difference of the proliferative index between schwannoma with LOH and that without LOH. The difference of the frequency of LOH in vestibular and spinal schwannomas was investigated by the chi-square test.

RESULTSTwenty-three schwannomas (42.6%, 23/54) showed allele loss. The frequency of LOH in vestibular schwannoma was significantly higher than that in spinal schwannoma (chi2 = 5.14, P < 0.05). The proliferative index of schwannoma with LOH was significantly higher than that without LOH (tki-67 = 2.97, P = 0.0045; tPCNA = 2.93, P = 0.0051).

CONCLUSIONSLOH on chromosome 22 is a frequent event in the tumorigenesis of sporadic schwannoma. And, there is a correlation between LOH on chromosome 22 and proliferative activity in schwannoma. The frequency of LOH in vestibular schwannoma is significantly different from that in spinal schwannoma.

Adult ; Aged ; Cell Proliferation ; Chromosomes, Human, Pair 22 ; Female ; Genes, Neurofibromatosis 2 ; Humans ; Loss of Heterozygosity ; Male ; Middle Aged ; Neurilemmoma ; genetics ; pathology ; Neuroma, Acoustic ; genetics ; Spinal Cord Neoplasms ; genetics ; Spinal Nerve Roots