Primary Intracranial Atypical Teratoid/Rhabdoid Tumors: A Clinicopathologic and Neuroradiologic Study.

Atypical teratoid/rhabdoid tumors are rare malignant pediatric brain tumors. This study was performed to characterize the clinicopathologic and neuroradiologic characteristics of atypical teratoid/rhabdoid tumors from 8 patients, including 5 male and 3 female infants (median age, 67 months). Neuroimaging revealed bulky masses of heterogeneous intensity with inhomogeneous enhancement. Three cases were infratentorial and 5 were supratentorial. Histopathologically, the tumors were predominantly composed of rhabdoid cells and undifferentiated small cells, mixed with some spindle or epithelial components. The tumors displayed striking polyphenotypic immunoreactivity, including varying degrees of positivity for vimentin, epithelial membrane antigen, smooth-muscle actin, cytokeratin, glial fibrillary acidic protein, neurofilament protein, synaptophysin, and CD99, and immunonegativity for desmin, placental alkaline phosphatase, and INI-1. The median survival duration was 9.5 months (range, 1-15 months) despite aggressive therapy. These results suggest that atypical teratoid/rhabdoid tumors display distinct clinicopathologic characteristics and indicate a poor prognosis. Immunohistochemistry facilitates the appropriate diagnosis of these tumors.