You can enable moderation for images that users upload for use in their user profile. When you do, the request to upload the image will appear in the moderation queue of a system-level content moderator. That person must approve the image before it will appear in the profile of the person who uploaded it.
Admin Console: People > Settings > Profile Image Moderation
This option is either fully enabled for all users or fully disabled for all users. This feature assumes you've already turned on the user Profile Image Visibility feature. For more about that, see Configuring User Customization.