Adverse reactions to injectable soft tissue fillers.

In recent years, injections with filler agents are often used for wrinkle-treatment and soft tissue augmentation by dermatologists and plastic surgeons. Unfortunately, the ideal filler has not yet been discovered and all of them may induce adverse reactions. Quickly biodegradable or resorbable agents may induce severe complications, but they will normally disappear spontaneously in a few months. Slowly biodegradable or nonresorbable fillers may give rise to severe reactions that show little or no tendency to spontaneous improvement. They may appear several years after the injection, when the patient does not remember which product was injected, and treatment is often insufficient. In this review, we discuss the most commonly used fillers, their most frequent adverse reactions as well as the characteristic histopathologic findings that allow the identification of the injected filler agent. In conclusion, histopathologic study remains as the gold standard technique to identify the responsible filler.