MR characteristics of malignant spinal cord astrocytomas in children

Abstract

Objective: Malignant spinal cord astrocytomas are rare tumors and their specific MR characteristics have not been previously described. We present a detailed MR analysis of four children with malignant astrocytoma. Methods: A review of the clinical database at the Hospital for Sick Children, Toronto revealed four patients with histologically-verified malignant spinal cord astrocytomas (WHO Grade 3 or 4) with pre-operative MR available for retrospective review. Results: There were three boys and one girl with a mean age at presentation of four years (range 7 months - 12 years). Mean duration of symptoms prior to presentation was six weeks (range 3 days - 5 months). Pre-operative MR analysis revealed that all tumors were located in the cervical or cervico-thoracic regions and expanded the cord over an average of 6.5 vertebral levels. The signal was usually hypointense on T1-weighted and hyperintense or mixed intensity on T2-weighted images. In the three cases where gadolinium was given, all demonstrated enhancement (one rim enhancement with a discrete border and two with inhomogeneous central enhancement). One tumor appeared to be exophytic, one had a significant cystic component, and none showed evidence of hemorrhage. Pre-operative leptomeningeal spread of tumor was documented in two of four cases and involved intracranial spread in both cases. Conclusions: There did not appear to be any specific MR characteristics to help differentiate a malignant astrocytoma from a low- grade tumor, except for the high rate of leptomeningeal spread at presentation. It is recommended that full neuraxis MR imaging be performed pre-operatively in children in whom a rapidly progressive clinical course suggests a malignant lesion. This will likely have a high positive yield and provide valuable information prior to surgical intervention.