Anaplastic PXA in adults: case series with clinicopathologic and molecular features

Pleomorphic xanthoastrocytomas with anaplastic features (PXA-As) are rare tumors about which little is known regarding clinicopathologic and molecular features. Several studies have identified BRAF V600E mutations in PXA-As, but the percentage with mutation may differ between adult and pediatric examples, and limited information exists about immunohistochemistry for isocitrate dehydrogenase 1 (IDH1). Ten cases of adult PXA-As seen at our institution since 2000 were assessed for BRAF V600E mutation by polymerase chain reaction testing (PCR) and IDH1 by immunohistochemistry. Patients ranged in age from 18-68 years; four PXA-As affected temporal lobe and two were cystic. Four patients underwent gross total resection and 9 of 10 patients received cranial irradiation and/or adjuvant chemotherapy. Five survived less than 5 years, although 2 of 5 patients died from non-tumor causes. Four long-term survivors are alive at 7.5, 9.8, 11.4, and 11.9 years post-diagnosis. Two of four long term survivors had BRAF V600E mutation: patients were ages 18 and 28 years. A 48-year-old male without BRAF mutation survives at 9.8 years, even with thalamic location; conversely a 68-year-old female with temporal lobe tumor and BRAF mutation survived 1.9 years after diagnosis. All tumors were IDH1 immunonegative. This case series details clinicopathologic features of a subset of rare PXA-As in adults. BRAF V600E mutation was identified in 50 % of these cases.