The Therapeutic Benefit of Allopurinol in the Treatment of Foreign Body Granulomas Caused by Polymethylmethacrylate Microspheres.

Background: Polymethylmethacrylate (PMMA) microspheres are permanent dermal fillers used in aesthetic procedures but may cause foreign body granulomas, resulting in chronic inflammation and discomfort. Allopurinol, a xanthine oxidase inhibitor with anti-inflammatory properties, has shown promise in granuloma management, although robust evidence remains limited. This systematic review aims to evaluate the efficacy and safety of allopurinol, alone or in combination with steroids, in treating PMMA-induced granulomas. Methods: We systematically searched PubMed, Embase, Scopus, Web of Science, Cochrane Library, and Google Scholar for English-language studies on human participants with PMMA-induced granulomas treated with allopurinol ± steroids. Eligible study designs included randomized controlled trials, cohort and case-control studies, case series, and reports. Two reviewers independently screened articles, extracted data, and assessed bias using Joanna Briggs Institute checklists. Qualitative synthesis was performed because of study heterogeneity and low evidence quality. Results: Out of more than 2500 articles identified, 6 studies (5 case reports, 1 case series; n = 8 women, aged 47-83 y) met the inclusion criteria. Granulomas developed 7 months to more than 10 years postinjection. Allopurinol (200-600 mg/d orally, 2-32 mo), alone or combined with steroids, lasers, or antibiotics, improved edema, erythema, tenderness, and nodularity, achieving partial or complete resolution in all cases. Reported adverse events were mild. Conclusions: Allopurinol seems to be a safe and potentially effective treatment for PMMA-induced granulomas, offering a steroid-sparing option. However, available evidence is limited to small, low-quality studies. Well-designed randomized controlled trials are needed to confirm efficacy and optimal dosing, and compare therapeutic strategies.