Chondroblastoma: the relationship between local invasiveness, recurrence, and histopathological features

This study aims to assess the histopathological and clinical characteristics of chondroblastomas (CBs), with particular emphasis on the correlation between local invasion and mitotic activity, cytological atypia, and recurrence.

A retrospective analysis was performed on 26 cases of CB diagnosed between 2016 and 2024 and pathologically evaluated at a tertiary oncology center, with surgical procedures performed across 2 tertiary oncology referral centers. Clinical, radiological, and histopathological data were reviewed. For comparative analysis, tumors were grouped as non-infiltrative (confined to the bone) or infiltrative (showing invasion of the bone cortex and/or extracortical connective tissues). Tumors were assessed for cytological atypia, mitotic index, matrix production, calcification, aneurysmal bone cyst formation, and invasion pattern. Immunohistochemical staining for S100, DOG1, and Ki-67 was conducted. Statistical analyses included t-tests, Mann-Whitney U, chi-square, and correlation analyses.

The mean age at diagnosis was 17.7 years, with a male-to-female ratio of 1.36 : 1. The femur was identified as the most common site. Invasion beyond the bone cortex was observed in 16 patients (61.5%), including 4 instances of soft tissue involvement. Invasive tumors showed significant association with moderate cytological atypia (P = .022), higher mitotic index (P = .023), and lower extremity location (P = .02). A positive correlation was identified between mitotic index and both atypia (P = .001) and tumor invasiveness. Recurrence occurred in four patients (15.4%), all presenting invasive tumors. No metastases were reported during the mean follow-up period of 38.9 months.

Although CB typically manifests benign behavior, a subset of these tumors demonstrates locally aggressive characteristics, such as cortical and soft tissue invasion. Elevated mitotic activity and moderate cytological atypia may serve as histopathological markers for local aggressiveness.   Cite this article as: Aygün MİŞ, .omunoğlu C, Doğan B, Adaş M, Tanrıtanır R. Chondroblastoma: the relationship between local invasiveness, recurrence, and histopathological features. Acta Orthop Traumatol Turc., 2026; 60(4), 0407, doi: 10.5152/j.aott.2026.25407.