The clinicopathologic study of foreign body granuloma induced by injection of filler

Background: With the popularization of soft tissue augmentation with dermal fillers, filler-related complications such as foreign body granuloma (FBG) are increasing. However, there has been no comprehensive study performed on FBG induced by dermal fillers in Korea to date. Objective: The purpose of this study was to investigate the clinicopathologic findings of FBG induced by injection of filler. Methods: Eighteen biopsy-proven cases of FBG due to injection of filler were reviewed and analyzed by their clinicopathological findings. In addition, the severity of grumilomatous inflammation was graded by the classification proposed by Duranti. Results: Two patients were injected with silicone, one with collagen and fifteen with unknown materials; they were treated by unlicensed practioners. The interval time between the injection and the presence of FBG ranged from 2 months to 30 years (mean: 2 years). Most of the lesions presented as skin-colored or erythematous subcutaneous nodules. In one patient, concomitant infection was discovered and the cultured organisms were coagulase negative staphylococcus and Mycobacteria chelonae. The histopathologic findings showed variable infiltrations of inflammatory cells, predominantly lymphohistiocytes and in fifteen patients (83.3%) multinuclear giant cells were also seen. In ten patients (55.6%), marked foreign body granulomatous inflammation of Duranti grade II were observed. In ten cases (55.6%), 'Swiss cheese appearance' representing granuloma due to lipoid materials such as silicone and paraffin were observed. Conclusion: This study shows various clinical presentations and histopnthologic findings of FBGs incurred by filler injections, although most of the injected materials were not identified. Further investigations on different injectable products are necessary to identify the nature of the injceted filler.