reading XML file and extract only node names and structure

I need to audit XML file structures and need to generate a report that shows only the DOM tree structure and omit the values. Essentially, I just the node names only and no values. I tried using xmllint and xmlstarlet but can't figure out how to do this. Does anyone know of any tools or examples of above tools that do this?

$filename.xml | xmlstarlet format -t

gives me what I need, but I want to omit all values.