MKI67 and pleomorphic xanthoastrocytoma: Previous reports have indicated that a high Ki67 LI index and BRAF status also correlate with malignancy in PXA.[7] The presence of BRAF V600E mutation, which is observed in 65% of PXA cases, is a predictor of favorable prognosis.[4,12,13] Tabouret et al. have reported that the BRAF V600E mutation is associated with lower Ki67 LI values;[13] however, both the cases described here exhibited a progressive clinical course despite the presence of the BRAF V600E mutation and absence of high mitotic activity, necrosis, or microvascular proliferation.