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Silicone
Silicone (polydimethyl siloxane), in a liquid, gel, or solid form, is used for tissue augmentation. While silicone is generally regarded as an inert substance, in some patients its use has been followed by foreign body reactions.
Clinical features
Silicone gel-filled implants are widely used for breast augmentation as well as reconstruction after mastectomy and leakage due to permeability loss or rupture can occur. Silicone injections and implants have also been employed for body and facial contour augmentation, including correcting HIV-related lipoatrophy. When a cutaneous foreign body reaction occurs, nodules and plaques develop at the site of injection or placement after a period of months to years. Skin lesions also appear at distant sites, reflecting the tendency for silicone to migrate, including in a dependent, gravity-driven direction. With progression, sclerosis and ulcerations can be seen. Whether the immune system is recognizing the silicone itself versus additives or contaminants including microbes remains speculative.
In a recent systematic review, hypercalcemia with renal failure was noted in association with silicone-induced foreign body granulomas and, to lesser extent, polymethylmethacrylate-, paraffin-, and mineral oil-induced foreign body granulomas. An increased risk of autoimmune connective tissue diseases (e.g. Sjรถgren syndrome, systemic sclerosis, rheumatoid arthritis) in patients with silicone breast implants has been observed in some, but not most, studies. Agreement does exist that textured breast implants, both saline and silicone, are associated with anaplastic large cell lymphoma of the breast.
Pathology
A biopsy specimen is critical to establishing the diagnosis. Histologic sections have a multivacuolated appearance due to the presence of silicone-filled cavities surrounded by histiocytes, lymphocytes, and eosinophils. The histiocytes may be foamy or multinucleated. Fibrous tissue within the areas separating the cavities is also seen. In contrast to paraffinomas, the cavity contents do not stain with lipid stains. Occasionally, silicone granulomas can mimic a low-grade liposarcoma.
Treatment
Excision of persistent symptomatic lesions is recommended.