Granulomatous reaction to hyaluronic acid filler following colonoscopy with colonic biopsy

Late-onset inflammatory reactions to hyaluronic acid (HA) fillers are rare but recognized complications, often associated with recent dental procedures, viral illness, and vaccination. We report the first possible case of late-onset granulomatous reaction to HA filler following colonoscopy with colonic biopsy. A 78-year-old woman abruptly developed multiple erythematous nodules on the submental chin, upper cutaneous lip, and cheeks one week after colonoscopy with biopsy. She had received HA filler injections to the chin, perioral region, cheeks, and jawline six months earlier. Skin biopsy confirmed granulomatous inflammation surrounding HA filler material. The patient was treated with a prednisone taper and doxycycline, resulting in marked improvement within one month and near-complete resolution by three months. This case highlights gastrointestinal procedures as a potential yet previously unreported trigger for late-onset filler reactions. Three potential mechanisms linking the gastrointestinal procedure to the late-onset filler reaction include: (1) transient bacteremia following mucosal disruption, (2) reactivation of dormant biofilm at filler sites, and (3) immune dysregulation due to bowel-preparation-induced dysbiosis. Host-specific factors, such as genetic predisposition including certain HLA haplotypes (e.g., HLA-B08, HLA-DRB103), and product-related factors, such as cumulative exposure to multiple filler types in the same facial region over time, may further modulate the risk and severity of delayed inflammatory reactions. Further research is warranted to elucidate the roles of systemic immune shifts and microbiome disruption in filler immunogenicity.