I live in Pennsylvania, I was wondering if anyone knows if you can be terminated while you are out on a medical excuse I had ovarian cysts rupture and did the proper procedures to call off and my boss terminated me during this time then she also said I misused office supplies without authorization and when I contacted Human resources the HR person told me that she did not know what that could be I have never been repremanded written or verbally about anything.

There are many options for you:-

1) Seek the help of top legal advice in the field.
2) Seek help from your Union if you belong to one.
3) Is there such a person as an ombudsman
In PA? if so get in touch with his office.

You have the right to medical leave and if they didn't write you up for anything it sounds like she is making things up.
While Pa is an at will employment state where they can fire you for no reason it does not mean that you can not pursue them for wrongful termination.
You need to pursue this.

I guess some questions, first you may not have a "right" to medical leave. Your company may have a policy how many sick days did you have, did you apply for an extended leave of absence.

How large of company is it, ( they may or may not fall under the Federal laws on leaves

If they are large enough ( over 50 people) how long have you been employed, ** have to have over 12 months employed.

If you work for a small company and only been there a short time, don't have any medical or vaction leave built up, yes it is possible that they may terminate you if you miss too many days.

For the theft of supplies you would have to had been warned

****I didn't know about the 50 people or more. Good to know.

Yes, I just went though a training course on that for my new job at the hospital. I actually read though the entire rules.