thank you for sharing your question with the Wefugees community.
As a Germany-based network we cannot give advice about the legislation in Italy, but I'll try to provide some general information, as immigration laws are quite similar in all EU-countries.
There exists a residence permit for the purpose of medical care in Italy, will you have to apply for it at the immigration office of the local police stations. (This can be done in written form, because I suppose they are closed now due to Corona). You also have to attach a deteiled medical clearance which includes diagnosis, treatment necessities and an assessment why your condition will probably deteriorate If it won't be treated in Italy.
I hope my answers were helpful and I’ll be very pleased if you contact me again with further questions. I'm a consultant with mbeon and I‘ll be glad to guide you over a longer period of time. mbeon is an online advisory service for migrants via app, which you can download on your smartphone for free. You'll find me in the mbeon-app under my name „München, Frau Müller“ and get confidential one-to-one advice in a safe virtual room where nobody can read messages. For further information please visit www.mbeon.de.