Atypical teratoid/rhabdoid tumor (AT/RT) is an uncommon but highly aggressive tumor that is usually seen in young children less than 2 yrs. of age. Most cases present as a posterior fossa mass, although it may occasionally be supratentorial in location (as in this case). In this T1-weighted MRI scan (with contrast) the tumor has cystic areas and shows heterogenous enhancement. Given the location of the tumor, choroid plexus carcinoma was considered in the differential diagnosis; however, histopathologic examination confirmed the diagnosis of AT/RT. Case produced with permission, courtesy of Dr. Frank Gaillard. Radiopaedia. Complete case is here.