H3F3B gene mutation in chondroblastomas: a multicenter study.

objectiveChondroblastoma (CB) is a benign but locally aggressive bone tumor that may present histopathologic diagnostic challenges, particularly in atypical locations and limited biopsy specimens. Recent studies have identified recurrent mutations in the H3F3B and, less frequently, H3F3A genes, suggesting their potential diagnostic value. This study aimed to evaluate the prevalence and diagnostic utility of H3F3A and H3F3B mutations in a multicenter cohort of CB patients.

methodsForty-three patients with histopathologically confirmed CB were included in a retrospective analysis. All cases were re-evaluated by 2 pathologists, and mutation analysis of H3F3A and H3F3B genes was performed using polymerase chain reaction-based Sanger sequencing.

resultsH3F3B mutations were detected in 41 cases (95.3%), all corresponding to the Lys36Met substitution. One case (2.3%) harbored an H3F3A Gly34Trp mutation, whereas 1 case (2.3%) showed no detectable mutation. No significant histopathological differences were observed between mutation-positive and mutation-negative cases. A notable case involved a 72-year-old patient with frontal bone involvement, highlighting the diagnostic difficulty in unusual locations and older age groups.

conclusionThe findings demonstrate that H3F3B mutation analysis is an extremely sensitive and reliable molecular tool for confirming the diagnosis of CB. It is particularly valuable in challenging cases and especially in small biopsy samples where pathognomonic findings, such as chicken-wire calcification and chondroid matrix are not visible. Incorporation of molecular testing into targeted diagnostic workflows may improve diagnostic accuracy and assist in distinguishing CB from its histological mimics.   Cite this article as: Tosun I, Yilmaz I, Cakir A, et al. H3F3B gene mutation in chondroblastomas: a multicenter study. Acta Orthop Traumatol Turc.,2026; 60(4), 0277, doi: 10.5152/j.aott.2026.25277.