Atypical teratoid rhabdoid tumor (AT/RT) is a rare and aggressive tumor usually occurring at younger ages. Pleomorphic xanthoastrocytomas (PXA) on the other hand are quiescent tumors with benign behavior. AT/RTs arising in the setting of PXA are exceptional. We present the case of a 23-year-old female patient, the fourth in the literature, speculated as having AT/RT arising within a PXA, as demonstrated by the presence of INI1 mutation. The patient presented with a short history of headache, which increased over time, and emerging seizures. She had a contrast-enhancing mass in the left temporal area demonstrated by MRI. Pathological examination demonstrated a dimorphic tumor containing a spindle-pleomorphic component reminiscent of PXA and a rhabdoid component with INI1 loss showing features of AT/RT. Both components shared the same BRAF mutation, supporting their common origin, and hence the case was speculated as an AT/RT arising in the setting of a PXA by secondary genetic change of inactivation of INI1. She had a poor outcome despite surgery and died 8 months after her diagnosis. .