The ornamental design for a topstructure for an internally illuminated handheld wand, as shown and described.
FIG. 1 is a front view of a top structure for an internally illuminated handheld wand, the back view, left side view and right side view being the same. A wand handle is shown with hidden lines to show orientation for the top structure for an internally illuminated wand.
FIG. 2 is a top view thereof; and,
FIG. 3 is a bottom view thereof.
The broken line showing is for illustrative purposes only and forms no part of the claimed design.