Atypical Teratoid/Rhabdoid Tumor in Adults an Uncommon Entity: A Case Report

Atypical teratoid/rhabdoid (AT/RT) tumor is a rare, highly malignant tumor of the central nervous system (CNS), most commonly found in children less than 5 years of age. Although the vast majority of cases are diagnosed in young children, there have been isolated case reports in adults. Since its histological appearance can be confused with other tumors, especially in adults, separating AT/RT from other neoplasms may be difficult. In many instances, a reliable diagnosis is not possible without demonstrating the lack of nuclear INI1 (SMARCB1) or BRG1 (SMARCA4) protein expression by immunohistochemical methods or by detection of somatic / germline mutation of the INI1 (SMARCB1) or BRG1 (SMARCA4) gene. Final diagnosis is confirmed after immunohistochemical analysis and/or molecular analysis. Immunohistochemical staining show that the tumor cells are positive for vimentin and reacted variably for keratin, epithelial membrane antigen (EMA), synaptophysin, neurofilament protein, CD34, and smooth muscle actin (SMA) and negative for GFAP, S-100, desmin and CD99. In adult examples of AT/RT, the diagnosis requires a high index of suspicion, with early tissue diagnosis and a low threshold for investigation with INI1 immunohistochemistry to differentiate this entity from other morphologically similar tumors. Although Abstract