Case reports: We describe three cases of atypical ATRT that were identified at the Children's Hospital of Eastern Ontario.
Discussion: Over the past decade, atypical teratoid/rhabdoid tumors (ATRTs) of the central nervous system have emerged as a distinct entity. This tumor is typically misdiagnosed as a primitive neuroectodermal tumor (PNET)/medulloblastoma. The unique immunohistochemistry profile of an ATRT helps distinguish it from a PNET/medulloblastoma. This is of clinical importance because the prognosis of a patient with an ATRT is worse than that of a PNET/medulloblastoma despite aggressive surgical treatment with or without adjuvant chemotherapy and radiation therapy.