Can you tell me if you have a positive mono test, can you be misdiagnosed?

Yes, Mono test is. Not a specific test for a given disease. Infection with many viruses can cause a positive "mono test". The commonest viruses are epstein barr virus and cytomegalovirus and a few other infections, so, it can lead to mis-diagnosis. See this site for more info. http://www.nlm.nih.gov/medlineplus/ency/article/003454.htm.