Abstract
BACKGROUND: Collagen-stimulating filler has boomed as a new welcoming option in aesthetic treatments by activating the synthesis of endogenous collagen. However, hyperactive or inappropriate foreign-body stimulatory reactions may trigger intractable foreign body granulomas (FBGs). A comprehensive understanding of the FBGs associated with the augmenting effect of collagen biostimulants can help clinicians perform treatments in a safer and more effective way. METHODS: A literature search was conducted in Web of Science, PubMed, Embase, and Scopus to identify relevant clinical reports about the FBGs induced by six types of commercially available collagen stimulators up to August 2024. RESULTS: A total of 40 studies involving 117 patients were included. All but eight cases were women, and the mean age was 52.63 years (range 29-78 years). The most reported cases of FBGs were associated with PMMA (35.04%), followed by PLLA (30.77%), CaHA (27.35%), PCL (4.27%), and dextran-based filler (2.56%). The time until initial detection of FBGs reaction ranged from 1 week to 15 years (mean 20.18 months). Nodules were the most frequent complication (82.91%), followed by swelling (9.40%) and lumps (3.42%). The perioral region was the reported high-risk region for FBGs. Intralesional injection of steroids was performed most frequently (21.37%), but symptoms were often resolved through surgical removal. CONCLUSIONS: All included collagen biostimulators can induce FBGs reactions, with the nondegradable fillers having a higher reported incidence and a longer latency period. Timely recognition, diagnosis, and appropriate management of FBGs behind tissue augmentation with collagen stimulator filler are necessary for clinicians to optimize efficacy and minimize adverse events. LEVEL OF EVIDENCE: V.