"Volcano sign"--description of a sign of aggressive neoplastic epidural lesions with subdural extension.

INTRODUCTION: Aggressive epidural intracranial lesions that break through the dura and develop an intra-axial component have been well-described previously in literature. However, there is no description of lesions with an epidural component and an exclusive subdural component without parenchymal extension in the pediatric patient.

DISCUSSION AND CONCLUSION: We have noticed a characteristic sign on cross-sectional imaging studies that indicates dural breakthrough resulting in a large extradural component and second subdural component, but no extraparenchymal component. This is best described as a "volcano sign" which characterizes the appearance caused by a focal break in the dural lining resulting in a sizeable subdural component from rapid lesion growth. In the pediatric patient, this sign is characteristic of a rapidly growing sarcomatous lesion, either primary or secondary.