Dr Peter Grossman, a burn and cosmetic surgeon, said he was optimistic the former Tonight Show host would make a full recovery.The hospital also released a photo of Leno smiling with hospital staff, with injuries visible to his jawline, neck and hands.Leno suffered serious and significant second-degree burns on 12 November in an explosion sparked while he was working underneath a vintage car in his garage.He received two skin graft surgeries while at the burn centre but Dr Grossman has said Leno remained in good spirits, even making jokes and once handing out cookies to children also being treated at the burn unit.In an episode last month, US President Joe Biden featured on the show, racing a 1967 Stingray Corvette at speeds of up to 118mph (190km/h)."