Italian to English Medical Medical (general) hospital names (?)

This may not be a medical term ... it appears in an emergency department report, and describes where the patient has been and will be treated:

"Pz in follow-up presso H.S.G. Monza" ... and later: "... attesa in data [xxx] presso ambulatorio di riferimento H.S.G."

I find many instances of this online, but never an expansion of the letters (example found online: " ... lavorano attualmente nel reparto della U.O. di Neurologia dell’Ospedale San Gerardo (HSG) in veste di medici specializzandi."

What does this stand for / how do we say it in English?

Thanks as always!