No need to apologize! But again, I think you're approaching this the wrong way. A question that begins with "is the provider required to perform..." is not one that a coder is qualified to answer. You're not going to find coding guidelines to answer that kind of question. Only the providers have the training to make a medical necessity judgment. It's a misconception that coders need to ensure medical necessity - that just not the case. Coders do need to be aware of medical necessity issues and to advise providers that documentation needs to clearly reflect their assessment and decision making, and also so that they can help providers understand and be aware that a payer may not agree with a particular treatment decision and therefore not cover a particular procedure or test. But ultimately the final decision of what is reasonable and necessary is up to the provider as that's what they're trained for. A coder is only trained to report what a provider documents, not to judge whether or not a service was necessary or required.
These are good questions you're asking, but I would put them to the provider. Let them know that you're understanding has been that a pathology report may be required for a cancer diagnosis and that you have a concern that if audited a payer might question why there wasn't a biopsied done first. If you have a copy of a payer policy that says this, then share it with them, (but honestly, I doubt you'll find one because payers don't get down to this level of detail in payment policies). Ask your providers their opinion on this question and if they think the records would be defensible as they are. But recognize that in the end, it's the provider's call as to whether or not to get a pathology report in this situation. If your providers tell you they're practicing according to accepted medical standards and they feel that their peers would back them up on how they're doing this, then I don't think you have anything to worry about. Hope that helps some.