"Another examination revealed that he's developed swelling of the vocal chords that is preventing a recovery," Jost said. "The cyst has to be surgically removed this week."
After the operation, Kaulitz will need several weeks to rehabilitate and avoid long term damage to his vocal chords, according to Bild.
"We really hope the fans will understand that Bill's health has to come first," Jost said.
The band's "1000 Hotels" European tour has been cancelled.