Pediatric Atypical Teratoid/Rhabdoid Tumor: Diagnosis Using Imaging Techniques and Histopathology

Atypical teratoid/rhabdoid tumor (AT/RT) of the central nervous system is an aggressive infantile embryonal neoplasm, usually presented as an intra-parenchymatous lesion. On Computed Tomodensitometry (CT) and Magnetic Resonance Imaging (MRI), AT/RT appears as a bulky, heterogeneous lesion, enhanced after contrast material injection. Both CT and MRI findings are similar to those seen in patients with Primitive Neuroectodermal Tumor/Medulloblastoma (PNET/medulloblastoma), consisting in the main differential diagnosis. Very few cases with diffusion, perfusion and spectroscopy data have been reported, but it seems that AT/RTs and PNET/medulloblastomas are not more distinguishable with more recent MRI techniques. One major histopathologic characteristic of AT/RT is the presence of rhabdoid cells, rarely predominant and not specific given that AT/RT contains variable components with primitive neuroectodermal, mesenchymal and epithelial features. Immunohistochemistry and genetic studies allow the differentiation between PNET/medulloblastoma and composite rhabdoid tumors. A precise diagnosis of AT/RT is important as this tumor has to be treated with intensive therapy (surgery, chemotherapy and radiation therapy). In spite of this treatment, the pronostic of AT/RT remains very poor.