ABSTRACT
<p><b>OBJECTIVE</b>To investigate the clinical and histological features of the complications after hydrophilic polyacrylamide gel injection.</p><p><b>METHODS</b>Fifty-two patients were included in this study, who had undergone hydrophilic polyacrylamide gel injection in other units from 1998 to 2003 and later came to our department for removal of the injected gel. The tissue samples taken from each cyst were sectioned and stained with hematoxylin and eosin. The sections were investigated and analyzed under light microcopy. The tissue sections of 12 patients who had ever received liquid silicone injection from 1988 to 1994 were used as the control group. The difference in histological features was assessed.</p><p><b>RESULTS</b>The inflammatory reaction of the hydrophilic polyacrylamide gel was characterized by an increased number of foreign-body giant cells. The mild lymphocyte infiltration was shown in the slides of hydrophilic polyacrylamide gel. On the contrary, there were much more clusters or lymphocyte infiltration in the slides of liquid silicone. The differences between the hydrophilic polyacrylamide gel and liquid silicone were significant in terms of thickness of the fibrous capsule.</p><p><b>CONCLUSIONS</b>The security of hydrophilic polyacrylamide gel injection for soft tissue augmentation is in doubt.</p>
