I think I have seen a sticky on this before. can you guys point me to it? I need to write a case report and do a literature review on a disease. thanks.
Pubmed (and other similar literature databases) are good places to start. Your med school library services should be able to help you out with this; most med schools have some sort of orientation to this process (literature searches and such).
IRB approval is generally not required since a case report is retrospective and all of the patient information is (should be) de-identified. IRB approval is usually reserved for research, not simply a case report, but check with your local institution on specific rules and expectations.
At my institution, the IRB gets to decide whether something falls within their purview, so you would have to submit your proposal for a case report to have the IRB "exempt" it from IRB oversight before you start seriously working in it. Kinda strange, eh? But, yes, as the previous poster said, a "case report" is generally not considered "human subjects research" under federal guidelines.