I can't find a single specific case. If you can, please post them here.Or in a matter of seconds Google will take you to many studies that are easy to find re pipe smoking and it’s associated risks, so why ask others to provided you with “cases” and claim they don’t exist?
A "study" can be flawed in a million ways. A case of a snüs user or a pipesmoker with lip cancer at the same point of contact after 30yrs consumption is much more convincing.