Occasionally, patients present with something they "found", that happens to have been there since birth, but was just stumbled upon. Here's what I've diagnosed in the past:
1. Circumvillate Papillae on the back of the tongue. If you can stick your tongue out far enough, you'll see several dimpled circles. The patient I saw said her husband refused to kiss her until she found out whether they were contagious.
2. Coronal Sutures. This patient was sure she had a brain tumor. Her suture had a little more of a ridge to it than average, but had been that way for several decades.
3. Nasal turbinates. I was asked to evaluate the growth in this child's nose on three separate occasions. At this point it was less humorous and more annoying. If you've ever looked in your own nose, the pink moist rounded things you see are the turbinates.
4. Bony prominence of the cervical spine was visible in the posterior pharynx of a particularly thin patient. Now, this one was a little weird for me too, but you can be sure it had always been there. In english, when she opened her mouth all the way you could see the a bump there from the underlying spine. What was really weird about it all was the fact that she kept reaching into her mouth and pushing on it to show me it didn't hurt.
I'm sure there will be more.