public static string Transform(string xmlData, string pathXsl)

        {

            string result;

            //Carico l'XML in un XmlDocument

            XmlDocument doc = new XmlDocument();

            doc.LoadXml(xmlData);

            XslCompiledTransform xslt = new XslCompiledTransform();

            xslt.Load(pathXsl);

            //StringWriter(derivato da TextWriter) per scrivere su stringa  *****

            StringBuilder sb = new StringBuilder();

            StringWriter sw = new StringWriter(sb);

            xslt.Transform(doc, null, sw);

            return sb.ToString();

        }