Well, he doesn't need to have a degree in everything he studied, of course.
He has a minimum of one Doctorate, or they wouldn't call him "Doctor"--presumably in physics. If Venkman of all people can have two doctorates, I don't see any problem with saying Egon has at least one more, probably in something more "Ghostbusterish"--ie, parapsychology, ancient history, as you suggest.
The closest I ever got in a story to a full summary, I think, was in
Busted:
Quote:
Spengler is a child prodigy who got his first physics degree at age twelve, going on to master such diverse and arcane fields as parapsychology, ancient languages, and mycology.
Now this is less official, but here goes:
He earned his Doctorate in Physics at MIT before going to Columbia for more "soft" subjects, such as linguistics, history, parapsychology, ect. per "Pandora's Box" and "Ghostbusting 101". I would presume he has a degree, if not a doctorate, in Parapsychology, which is what he's studying in "Ghostbusting 101" (where he also meets a slacker named Peter Venkman).
He's definitely mastered a number of languages. In canon, sign language, Sumerian, Mesopotamian, and whatever (presumably Nordic-related) language the Ragnarok message was written in, of which he's only one of three people in the world capable of reading as of 1984. Furthermore, knowledge of Greek and Latin would seem almost a no-brainer; on the other hand, per an EGB episode, he's not very fluent in Spanish.
A background in Forensics, if not an actual degree, is mentioned in both the video game and hinted at in the EGB episode "Killjoys". I really don't see him as being a full MD though.
This is even less official, because I never even stated it in a story, but I actually tend to think he doesn't have any formal degree in mycology, since it's his "hobby"
So basically, definitely a PhD in Physics, probably at least one more PhD in either Lingustics or Parapsychology (if not both), and at least some education in Forensics. Mycology mostly self-taught.
Hm...this might be an interesting look for ideas, though:
http://en.wikipedia.org/wiki/List_of_fi ... al_studies