I. Background. The Armed Forces institute of Pathology (AFIP) Breast Implant Project was begun in February, 1993 and received final administrative approval by the AFIP Research Committee on June 13, 1993. Departments of pathology from military and civilian hospitals were invited to participate in this pilot project.

II. Current Status and Materials Available. A representative variety of implants have been received. Capsular tissues are available in approximately 75 percent of cases. To date, ~175 cases have been received for study. Light microscopic examination has been completed in those cases where tissue is available, and reports of these findings have been sent to the contributors.

III. Pathology. Fibrosis is uniformly present and seems to be particularly restrictive where synthetic mesh patches have been applied to the implant for stabilization purposes. Macrophages with foamy cytoplasm are identified in the majority of implant capsules. Inflammation is generally minimal and, where present, is chronic in nature.

Spiculated, birefringent material identified as magnesium silicate (talc) has been identified in capsular tissues in over 50 percent of cases examined histologically, results entirely similar to those published by other groups. The origin of this material remains uncertain. In addition, we are in the process of attempting to characterize a progressive papillary response at the implant/capsule interface that occurs in a minority of cases.

IV. Biophysical Studies. Capsular tissues have been sectioned onto mirrored slides for microspectroseopy studies using Fourier-transform infrared spectroscopy (FT-JR) and laser Raman microprobe (LRM). Similarly, sections have been prepared onto carbon disks for SEM/EDXA studies. FT-IR and LRM have confirmed the presence of silicone in approximately two-thirds of cases where capsular tissue is available. Other studies include the examination of individuals with saline implants who are known not to have been previously implanted with silicone gel, to ascertain the presence of silicone and/or talc in these capsular tissues. Studies are in progress to examine blood and urine from implanted, explanted and control patients for the presence of elemental silicon, with correlation with immune and other clinical symptomatology.

1. Histopathologic and Laser Raman Microprobe Analysis of Regional Lymph Nodes from Patients with Silicone Breast Implants. Regional lymph nodes from patients with breast implants frequently have histologic evidence of silicone migration. Characteristic findings include the presence of foamy macrophages and refractile droplets of clear material consistent with silicone. Polygonal fragments of polyurethane were observed in lymph nodes from multiple patients. These findings have not been previously reported. The presence of relatively large particles of foreign material in regional lymph nodes may provide some insight into the mechanism of the metastatic process. We plan to continue with the acquisition of Raman chemical imaging and morphological analysis.

V. Cases from Foreign Nationals. Currently, the Registry contains approximately 16 cases from foreign national contributors (Mexico). Clinical data, case paraffin-block, slides and reports are available in all these cases.

VI. Publications and Published Abstracts. Several manuscripts, published abstracts, contributed lectures, presentations and course materials have resulted from the material and research available at this Registry. A list of these activities is provided below.

VII. Publications:

1. Centeno JA, Mullick FG, Panos RG, Miller FW, and Valenzuela-Espinoza A. Laser-Raman Microprobe Identification of Inclusions in Capsules Associated with Silicone Gel Breast Implants. Modern Pathology 1999; 12(7):714-721.
2. Van Dyck K, Robberecht H, Van Cuawendergh, RV, Deelstra H, Arnaud J, Benijts F, Centeno JA, et al. Spectrometric Determination of Silicon in Food and Biological Samples: An Interlaboratory Trial. Submitted for Publication:Journal of Analytical Atomic Spectrometry 2000.
3. Luke JL, Kalasinsky VF, Turnick RP, Centeno JA, Johnson FB, Mullick FG. Pathological and Biophysical Findings Associated with Silicone Breast Implants: A Study of Capsular Tissues from 86 Cases. Plastic and Reconstructive Surgery 100;1558-1565:1997.
4. Centeno JA, Ramos, MS, Mullick FG, Offlah OO, Rastogi T, Panos RG. Biophysical Findings Associated with Silicone-Gel Breast Implants: Deten-nination of Silicon, Calcium and Magnesium Levels in Capsular Tissues. Metal Ions in Biology and Medicine, Vol. 5. Eds Collery P, et al., John Libbey Eurotext, Paris. pp. 362-366; 1998.
5. Jackson LW, Dennis GJ, Centeno JA. Analytical Determination of Blood Silicon in Patients with Silicone Breast Implants. Metal Ions in Biology and Medicine, Vol. S. Eds Collery P, et al., John Libbey Eurotext, Paris. pp. 33- 38; 1998
6. Centeno JA, Johnson FB. Microscopic Identification of Silicone in Human Breast Tissues by Infrared Microspectroscopy and X-ray Microanalysis. Applied Spectroscopy 47(3); 341-345: 1993.

Abstracts Published

1. Centeno JA, et al. Biophysical Characterization of Silicone Breast Explants by Laser Raman Microprobe and Infrared Microspectroscopy. Preprints American Chemical Society (Division of Environmental Chemistry) 34(2); 132-135; 1994.
2. Centeno JA, et al. Electrothermal Atomic Absorption Determination of Silicon in body Fluids and Tissues Specimens. Preprints American Chemical Society (Division of Environmental Chemistry) 34 (2); 13 1; 1994
3. Centeno JA, et al. Microprobe Analysis of Pathological Inclusions in Fibrous Capsules Associated with Silicone Breast Implants. 86' Annual Meeting of the United States and Canadian Academy of Pathology, Human Pathology 10(l): 1062A; 1997.
4. Katzin WE, Centeno JA, Feng L-J, Kiley M, Mullick FG. Pathology of Lymph Nodes from Patients with Breast Implants: A Histologic and Spectroscopic Evaluation. Proceedings of the United States and Canadian Academy of Pathology, 2002.