Washington [US], October 22 (ANI): Pop icon Ariana Grande has publicly apologised to Cassandra Peterson, famed for playing horror host Elvira in ‘Elvira: Mistress of the Dark’, according to The Hollywood Reporter. Ariana has reacted to Elvira’s recent comment that the singer declined a photo with her. Recently, a video of Cassandra went viral in which she can be heard saying at the Knotts Berry Farm event that one of her worst celebrity encounters was when Grande arrived to attend Elvira’s performance and later refused to take a photo with Peterson. “I’ll tell you briefly… she came and she b…