[An atypical rhabdoid/teratoid tumor. A presentation of three cases and review of the literature].

Introduction: The atypical rhabdoid/teratoid tumor of the central nervous system (CNS) has emerged from a variant of medulloblastoma to become a distinctive clinico-pathological condition over the past ten years. This is more than simply nosological importance, since the five year survival expected in medulloblastomas is considerably better than the 11 months (average) seen in rhabdoid/teratoid tumors.

Objective: To describe the main clinico-pathological characteristics of a recently recognized condition, emphasizing its polymorphism and differential diagnosis.

Patients And Methods: We report the clinical, radiological, cytohistopathological and immunohistopathological aspects of three atypical rhabdoid/teratoid tumors diagnosed in the Hospital A.B.C. of Mexico City.

Results: The three tumors were seen in boys aged 18 months, 5 years and 14 years, localized to the right cerebellum, left cerebral hemisphere and left cerebellum, respectively. Different markers were shown including: vimentin, cytokeratin, epithelial membrane antigen, gliofibrillare acid protein, synaptophysin, alpha fetoprotein, S100, (HHF-35) actin, cromogranin, neurofilaments, human chorionic gonadotrophin, placental alkaline phosphatase, desmin, CD99 and carcinoembryonary antigen. We established the morphological similarities and differences in our cases, and noted the profuse vascular proliferation which in one case resembled vascular neoplasia. We compared our results with other published cases.

Conclusions: The atypical rhabdoid/teratoid tumor of the CNS may easily be confused with other primary or metastatic tumors since the rhabdoid characteristics do not only occur in this tumor. Also the rhabdoid aspect may be less marked and in some cases does not predominate. Some zones of the tumor may be identical to other embryonic tumors of the CNS and the immunophenotype be superimposed on that of other neoplasias of the nervous system.