A rare and incurable disease that causes the sufferer to display overly dramatic and attention seeking symptoms.

More advance causes may seem very similar to cancer, however it's phantom cancer that doesn't actually exist.

Sometimes the victim may consider self harm or suicide. This is also made up.

It is caused by overly dramatic teenage/childhood experiences, however it is often the case that it's all a delusion.

Briefly, "the realization that each random passerby is living a life as vivid and complex as your own." Originally from the Dictionary of Obscure Sorrows, which has a lot more beautiful neologism definitions like this you might enjoy.