Arteriovenous malformation associated with anaplastic astrocytoma
In patients with intracranial hemorrhage in an unusual area like our case, it is essential to perform angiography to differentiate AVM from other vascular lesions. Angiography remains the standard method to evaluate the architecture of AVM. Most cases in the literature were diagnosed of AVM pre-operatively and then coexistence of high grade glioma was noted in the pathology examination. In cases with obvious radiological appearance of tumor pre-operatively, the establishment of the association with an AVM was confirmed during operation. Pre-operative angiography for precise information of the vascularity and displacement of normal vessels should be considered in patients with a diagnosis of brain tumor: in that way, an association of an AVM with a brain tumor could be demonstrated pre-operatively .
According to the 2007 World Health Organization(WHO) classification of tumors of the central nervous system, the WHO defines diffusely astrocytic tumors with cytological atypia as grade II (diffuse astrocytoma), those also showing anaplasia and mitotic activity as grade III (AA), and tumors additionally showing microvascular proliferation and/or necrosis as WHO grade IV. In addition to the WHO classification system, the Ki-67/MIB-1 labeling index is often included in pathology reports. The current WHO classification of human astrocytomas has limitation in predicting prognosis and diagnosis. All studies show increasing value of Ki-67/MIB-1 labeling index with increasing grade of malignancy. They show an average value of MIB-1 in the three groups of grade II astrocytoma, AA and glioblastoma multiforme (GBM) of approximately 3,12, and 16 respectively. Some studies also identify significant differences when comparing grade II with grade III and grade II with grade IV, but not when comparing the differences between grades III and IV . GFAP is a specific marker for immature, reactive, and neoplastic astrocytes and ependymal cells. Although the absence of GFAP in a neoplasm does not exclude an astrocytic origin, the presence of GFAP indicates astrocytic or ependymal differentiation. This has important diagnostic applications. The expression of GFAP is used to distinguish astrocytic neoplasms from epithelial or mesenchymal tumors that may on occasion mimic a glioma . High grade astrocytoma is impressed according to the result of high MIB-1/Ki-67 labeling index and strongly positive reaction with GFAP. Due to the absence of glomeruloid microvascular proliferation, areas of necrosis and pseudopalisading around areas of necrosis, GBM is less possible in our case .
We present an unusual case with coexistence AVM and AA. After the operation, left side hemiplegia and aphasia are noted due to left side middle cerebral infarction. There is no residual vascular lesion noted on the subsequent angiography. MRI for follow up showed residual brain tumor over the left lentiform nucleus. Further concurrent chemotherapy and radiotherapy was arranged for this patient.
Contributed by Hui-Yuan Su, MD, Chia-Mao Chang , MD, Kun-Bow Tsai.MD, Yu-feng Su, M.D.