Risk factors for local recurrence from atypical cartilaginous tumour and enchondroma of the long bones

Introduction: The purpose of our study is to verify possible clinical and radiological findings with regard to distinguishing enchondroma from atypical cartilaginous tumour (ACT). In addition, this study determined risk factors that are associated with local recurrence of enchondroma or ACT treated with curettage. Materials and methods: We retrospectively reviewed the records of 54 patients with enchondroma and 35 patients with ACT of the long bones treated by curettage between 1986 and 2015. The minimum follow-up was 18 months. The relationship between clinical and radiological factors and the tumour type or local recurrence was assessed using Chi-square test or Fischer exact test. Results: Endosteal scalloping (p = 0.004) and soft tissue extension (p = 0.017) were shown to statistically favour ACT over enchondroma; by contrast, pain (p = 0.034) was more frequent in enchondroma compared to ACT. All patients with enchondroma had no local recurrence; in contrast, local recurrence occurred in four patients with ACT (11%). Soft tissue extension (p = 0.049) and the diagnosis of ACT (p = 0.021) were associated with an increased risk of local recurrence. We had a disease progression in three of four patients with local recurrence, and these had higher histological grade than the original tumour. Discussion: Our data show that endosteal scalloping and soft tissue extension could be helpful in the differential diagnosis between enchondroma and ACT. We suggest following only those patients with ACT after surgery to identify any possible recurrence and, in case of recurrence, treat these patients with resection for the risk of disease progression.