Can Renuva be used in the pyriform fossa?

Yes, generally Renuva can be injected here. Other good options if you are trying to avoid HA (though some HA swells much more than others) would be fat grafting or Radiesse, depending on what you look like and what your goals are.

Renuva has not caught on as a popular product. HA products are pretty forgiving and if that causes swelling then you can probably expect any substance injected will cause swelling.
Renuva really has been proven to be particularly good.
Best,
Mats Hagstrom MD