Each IRB chairman and the Director, ORI has the authority to determine if a study qualifies as human subject research and the subsequent category in which it may qualify.
Requests for determinations as to whether or not a thesis/dissertation involves human subject research should be sent to the Director, ORI.
Case studies/presentations with literature review but without further analysis have been regarded as a medical education activity, not research at all. In this situation, no IRB notification or classification should be required since it is not human subject research for IRB purposes.
Of course, if you are unsure whether an activity is human research or not, you should contact the Office of Research Integrity and submit an abstract for a judgment on that point.