Wilkie T F
Plast Reconstr Surg. 1977 Aug;60(2):179-88. doi: 10.1097/00006534-197708000-00004.
In a 10-year experience with silicone injections involving 92 patients, there was subsequent development of a granuloma in 13 injection sites. Most of these occurred within 12 months, but some took a few years and one appeared 7 years later. It is believed that the injected material was medical grade liquid silicone, without additives or contaminants.