Mas-Blanc-des-Alpilles is a commune of 373 people ( 1999 ) . It is found in the region Provence-Alpes-C Ã te d'Azur in the Bouches-du-Rh Ã ne department in the south of France . Mas-Blanc-des-Alpilles is a commune in the Bouches-du-Rh Ã ne department in southern France .