Atypical teratoid/rhabdoid tumor of the central nervous system in children: an atypical series and review.

Primary atypical teratoid/rhabdoid tumor (AT/RhT) of the central nervous system is a recently described, highly malignant neoplasm in infants and young children. This tumor is an unusual combination of mixed cellular elements, similar but not typical of teratomas, and rhabdoid cells. This tumor is most common in the posterior fossa in children less than 2 years, and is radiologically similar to medulloblastoma. No pathognomonic imaging features are present. The two tumors can be separated on histologic, molecular, and cytogenetic grounds. Separation of these two tumor types is crucial because the prognosis for AT/RhT is grim even with current multimodality treatment. We present four consecutive cases of AT/RhT, three in locations other than the cerebellum, seen at our institution in a 14-month period, indicating that this tumor may be more common than previously thought.