CPE, HOST-T and IT-Grundshultz show up on the Vulnerability Scan Detail report as open ports, but they are not a specific port, but rather log information that a particular set of ports were scanned using those extension modules.
Just like CVE and NVT, the above modules represent other tests as defined by their respective organizations. They will show up in the port lists to indicate the tests were performed, but should be taken as informational data only.
More information can be found about CPE at http://cpe.mitre.org
Information on the IT-Grundshultz can be found at https://www.bsi.bund.de