Hi, thank you for your suggestion. I assume you are referring to United States Metropolitan Statistical Areas? This is a map we will consider adding to our map collection. For now, you can create your own map and add it to Highmaps, see http://www.highcharts.com/docs/maps/custom-geojson-maps and http://www.highcharts.com/docs/maps/custom-maps.

Regarding TopoJSON you currently have to convert this into either SVG paths or GeoJSON format to use it with Highmaps. There are multiple tools available for performing these conversions. Also see https://highcharts.uservoice.com/forums/55896-highcharts-javascript-api/suggestions/6074726-support-topojson