Capsular formation around silicone implants stained with methylene blue. An experimental study

Recently, most of immediate breast reconstruction following mastectomy is being carried out with use of silicon implants. In these patients, methylene blue is being used for the detection of sentinel lymph node. The inflammatory effect of methylene blue (MB) can exert a negative effect on the capsule formed around breast implants. This experimental study was performed to determine whether methylene blue can aggrevarte capsular contracture or not following breast reconstruction. In this study, a total of 32 Sprague Dawley rat weighing between 250-300 grams were used. These rats were grouped equally into 4 groups. Costum made silicone implants in the size of 1 cm3 are placed under panniculus carnosus muscle on the back of animals. In the first control group, the incision was closed without performing any additional procedure. In the second control group, 0.1 ml of 0.9% normal saline was instilled into the pocket, before the incision was closed. In the third and fourth study groups, 0.1 and 0.2 ml of 1% MB was injected into the pocket, respectively. On postoperative day 60, silicon implants and capsular tissue were extracted. Capsule formation was evaluated both macroscopically and microscopically. Histologic evaluation included were, in addition to capsule thickness, inflammation, neovascularization and fibrosis gradients. Capsule thickness was measured as a mean of five different points on ventral, dorsal and lateral aspects of each implant in each group. The severity of inflammation, vascular proliferation and fibrosis were evaluated from 0 to 4 based on the gradient of each in a given slide. Regarding capsule thickness, there was a statistically significant differences between groups I-III, I-IV, II-III and II-IV (p=0,004; p=0,024; p=0,001; p=0,009, respectively). Although there was more of moderate and severe inflammation gradient in groups III and IV, there was no significant difference regarding inflammation severity between control and study groups. In respect of vascular proliferation, there was an statistically significant difference in between control and study groups (p=0,014). Similarly, fibrosis gradients were higher in both groups III and IV (p<0,001). There was visible increase in inflamattory cells, new vessel formation and fibrosis gradients beside increased capsule thickness in groups treated with MB. In this study; we proved that injection of methylene blue around silicone implants is enhancing the formation of capsular contracture. In this case, the degree of contracture is independent on the dose given. Key words: breast reconstruction, capsular contracture, methylene blue, silicone implants.