Depends on what version of PAN-OS you're on.
From version 6.1.X on, you're good. Follow these guides (Essentially you'll just want to create a custom URL Object and use it in policy based upon how you desire to allow or deny on a case by case basis:
https://www.paloaltonetworks.com/documentation/61/pan-os/pan-os/url-filtering/block-and-allow-lists#14516
"For example: If you want to prevent a user from accessing any website within the domain paloaltonetworks.com, you would also enter *.paloaltonetworks.com , so whatever domain prefix (http://, www, or a sub-domain prefix such as mail.paloaltonetworks.com) is added to the address, the specified action will be taken. The same applies to the sub-domain suffix; if you want to block paloaltonetworks.com/en/US, you would need to add paloaltonetworks.com/* as well."
https://downloads.paloaltonetworks.com/software/PAN-OS-6.1.0-RN.pdf?__gda__=1465314609_557613dbafd2ac5ed438dd389a7f9018
"PAN-DB can now categorize content down to the page level instead of just at the directory level. Because the pages within a domain can belong to multiple categories, this capability provides increased accuracy in filtering content and prevents potential over-blocking of web content. If, for example, you block malware and allow access to business/ news content for users on your network, they can access http://www.acme.com/c/news.html because it is categorized as news/business, but be denied access to http://www.acme.com/c/malware.exe because PAN-DB categorizes the full-path for this web page as malware. "
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