There is no way to run a context scan on files to check for malware on Windows 10 using the built-in Windows Defender Antivirus.
Thanks, I never played with Windows Defender on anything but Win7.No. It has been this way since the Launch of Windows 8, likewise for 8.1 and now, 10.
This may work for Windows 10:
http://www.tenforums.com/tutorials/6120-windows-defender-context-menu-add-windows-10-a.html
Or methods for Windows 8/8.1:
http://www.howtogeek.com/137083/how...ws-defender-to-the-context-menu-in-windows-8/
http://www.askvg.com/how-to-add-scan-with-windows-defender-option-in-file-context-menu-in-windows-8/
It was added to Windows 10 November Update (2015) - (Source)Probably it was added during the updates ( now I see the thread started in July )