Thought a bit more how people use Drupal CMS to update categories. Categories will be taxonomies in a view so that they can refer nodes to the categories.
Also at the most when click on category, it will be either a full taxonomy page or node page.
Sidebar will have taxonomy categories on left column and right column will explain more information. So if it is on same taxonomy, the menu item will be highlighted to let user know where they are on.
The problem is how to add sidebar to either taxonomy page or node page and set menu item active / highlighted?