PROM1 and pilocytic astrocytoma: In 3 of 18 (17%) pilocytic astrocytomas (PAs), 1 of 1 (100%) grade II astrocytoma (AST), 2 of 2 (100%) gangliogliomas (GGs), and 1 of 1 (100%) PXA, CD133−/CD15+ cells accounted for >30% of the total cell population (Figure 2B), demonstrating CD15+ cells in PLGGs for the first time.