The complicated cavity of this disease is caused by necrosis, liquefaction or local necrosis and suppuration caused by secondary infection of pyogenic bacteria in foci, and they pass through the trachea and causes the disease; 本病并发空洞是病灶发生坏死、液化或由于继发化脓菌感染引起局部坏死化脓,使其经气道排出后形成;