Introduction: A prospective study was performed to analyse the cellular and molecular composition of fibrous capsules around silicone breast implants. The necessity of an exact histological classification for comparing objectively the different findings of capsular contracture is shown.
Patients and methods: The prospective study (investigation time 1/2003 to 6/2005) included 24 female patients (average age: 40+/-12 years) with contracture after bilateral cosmetic breast augmentation with smooth silicone gel implants (Mentor). In each patient the baker score was determined preoperatively. Samples of capsular tissue from all patients were evaluated histologically and immunohistochemically and classified according to the histological classification introduced by Wilflingseder and co-workers.
Results: All capsules showed the same basic histological structure with a three-layer composition. For the correlation analysis we had to exclude one patient with repeated implant change. There was no correlation between the patient's age, time of implantation, length of implant period, and capsular contracture. Greater amounts of silicone particles were associated with increased degrees of capsular contracture (Baker: r = 0.687, n = 23, p < or = 0.001; Wilflingseder: r = 0.784, n = 23, p < or = 0.001). High silicone amounts were associated with an increased local inflammation (r = 0.489, n = 23, p , 0.05). A moderate to severe local inflammation was found in 23 patients (95.8%). In summary, there was a positive correlation (r = 0.797, n = 23; p , or = 0.001) between the clinical classification (Baker score I to IV) and the histological classification (Wilflingseder score I to IV).
Conclusions: We demonstrated in our study, in spite of using implants with high gel cohesiveness (fourth generation), the presence of vacuolated macrophages with microcystic structures containing silicone and silicone particles in the capsular tissue. Greater capsular thickness was associated with an increased number of silicone particles ans silicone-loaded macrophages in the peri-implant capsule. The histological classification introduced by Wilflingseder and co-workers takes into consideration this pathogenetic mechanism of inflammatory reaction which seems to be one of the major key factors in the development of capsular contracture.