Does Silicone Gel Migrate Via Lymphatics After Subcutaneous Injection?

PP Narini, JL Semple, JB Hay, SJ Lugowski, D Smith. Does silicone gel migrate via lymphatics after subcutaneous injection? Can J Plast Surg 1994;2(2):67-70. Reports have documented the presence of elemental silicon, evidence of silicone elastomer, or silicone polymers (gel) in lymph nodes and other sites distant from implanted prostheses. It has been suggested that this occurs via the lymphatic system; however, the mechanism of spread or migration of silicone has not been previously studied. This study investigated the possible role of lymphatics in the migration of silicone gel. In the sheep model, it is possible to obtain continuous samples of both afferent and efferent lymph by cannulating lymphatic vessels. The drainage areas of subcutaneous lymph nodes in the sheep have previously been studied. In our model, the efferent lymphatic vessel from the prefemoral lymph node was cannulated to obtain samples of lymph (efferent and ‘pseudoafferent’). After baseline samples were collected, 3 to 5 mL of free silicone gel was injected subcutaneously in the drainage area of this node. Samples (5 to 10 ml.) of lymph were continuously collected (for up to 50 days), sealed, stored at −20°C, and then submitted as a group for trace element analysis to quantitate the levels of elemental silicon. No statistically significant increase was seen in baseline levels of elemental silicon after silicone gel injections. Statistically significant higher levels of silicon were found in afferent (mean 799 ± 22 part per billion [ppb]) compared with efferent lymph (mean 607 ± 19 ppb). This experimental study did not identify significant increases in elemental silicon levels in lymphatic vessels after the subcutaneous introduction of free silicone gel. Higher levels were found in afferent versus efferent lymph. This implies that migration of silicone gel does not occur soon after the exposure of a subcutaneous space to free silicone gel, or that the migration of silicone gel may occur by a cellular mechanism that can bypass the lymphatic vessels.