Risk of Malignancy in Asymptomatic Unilateral Tonsillar Enlargement in Adults and Children: A Systematic Review and Meta‐Analysis

Background Unilateral tonsillar enlargement (UTE) may raise concern for malignancy and frequently prompt diagnostic tonsillectomy. However, when present in the absence of additional suspicious features, the true risk of malignancy remains uncertain. This study aimed to evaluate the prevalence of malignant histology in patients undergoing tonsillectomy for isolated asymptomatic UTE. Methods A systematic review was conducted in accordance with PRISMA guidance. MEDLINE, EMBASE, EMCARE, PubMed and the Cochrane Library were searched from inception to 22 September 2025. Studies reporting histopathological outcomes in patients undergoing tonsillectomy for isolated asymptomatic UTE were included. A meta‐analysis of proportions was performed for adult‐only cohorts. Results Eighteen studies comprising 1582 tonsillectomy specimens met the inclusion criteria. No malignant cases were identified in paediatric patients (0/751; 95% CI 0.00%–0.49%). Among adult patients ( n = 712), six malignant cases were identified, all of which were lymphoproliferative in origin. Meta‐analysis of adult‐only studies demonstrated a pooled prevalence of 2.04% (95% CI 0.98%–4.22%) with low heterogeneity ( I 2 = 15.2%). The crude overall prevalence of malignancy across all cohorts was 0.38% (95% CI 0.14%–0.82%). Conclusion Isolated asymptomatic UTE is associated with an extremely low risk of malignancy, particularly in paediatric patients. Routine diagnostic tonsillectomy is unlikely to be justified in children and should be selectively considered in adults based on clinical risk factors. Careful clinical assessment remains essential in guiding management.