Magnetic resonance feature of “paintbrush borders” sign as a novel way to predict recurrence of giant cell tumor of bone after curettage: a pilot study

OBJECTIVE: To identify the prognostic factors for local recurrence of giant cell tumor of bone (GCTB) through assessment of the preoperative imaging features of the tumor border. METHODS: Patients with GCTBs treated with intralesional procedures in the proximal tibia and distal femur were prospectively enrolled and then followed up for at least 2 years. The GCTBs were grouped according to their preoperative imaging features. GCTBs treated with en bloc resection were enrolled for investigation of the pathologic basis of specific imaging features. Differences between rates were evaluated by the chi-square test or Fisher’s exact test; independent factors were identified by multivariate logistic regression analysis. RESULTS: Fifty-three patients were enrolled and successfully followed up. Relapse occurred in 22 patients. Patients with a “paintbrush borders” sign (n = 21) had a significantly higher rate of local recurrence (71.43%) than patients without this sign (21.88%). The “paintbrush borders” sign was identified as an independent prognostic factor for local recurrence. Other imaging features were not significantly associated with recurrence. The “paintbrush borders” sign showed a correlation with local invasion of bone. CONCLUSION: The “paintbrush borders” sign on preoperative magnetic resonance imaging is an independent prognostic factor for local recurrence of GCTB.