What is T2 hyperintense mass involving the brainstem in a child?

A T2 weighted image, on a MRI, is not diagnostic, in and of itself. T2 hyperintensity could represent tumor, infarction, hemorrhage, or trauma, for instance. In the context of the clinical picture, the MRI is extremely helpful. If there has been no trauma, then the location and appearance of the T2 hyperintensity can point to a vascular cause versus a space-occupying lesion. The clinical course of the patient will cinch the diagnosis, when combined with the MRI findings - in cases such as these.

In the case of a mass in the brainstem of a child, the most common cause would be that of a brainstem glioma. These account for anywhere between 10-20% of all brain tumors in children. However, this is not the only possibility (see above).