Mumbai Actor Emraan Hashmi, who has penned a book about his struggles with his son Ayaan's cancer treatment, has thanked megstar Amitabh Bachchan for wishing good health to the six-year-old. He also called Big B the "original superhero". The 73-year-old had sent a note for Ayaan, who was diagnosed with first stage cancer at the age of four in early 2014. Emraan even shared the photograph of the note sent by the "Piku" star. The note was in a white envelope, which read: "Master Ayaan Hashmi". "Emraan Hashmi, really what a remarkable son... God bless him and may he remain healthy ever," Big B tweeted on Saturday night. Thanking the "Sholay" actor, Emraan tweeted: "Thanks Amitabh Bachchan for the note. Ayaan aspires to be Batman. And Batman aspires to be you. You are the original superhero!"