Lumbar atypical teratoid/rhabdoid tumor in an adolescent: integrated histopathological and molecular diagnosis, a case report

Atypical teratoid rhabdoid tumor is a rare, highly aggressive embryonal neoplasm of the central nervous system, and primary spinal presentations in older adolescents are exceptionally uncommon, with very limited comparative data in the literature. We report a 17-year-old male with cauda equina syndrome due to an intradural lumbar lesion initially interpreted radiologically and intraoperatively as myxopapillary ependymoma or schwannoma. Histopathological findings revealed a highly cellular small round blue cell tumor with rhabdoid morphology, high proliferative activity and complete loss of nuclear SMARCB1/INI1 expression. DNA methylation profiling assigned the lesion to the atypical teratoid rhabdoid tumor MYC molecular subgroup with SMARCB1 loss-of-function. The patient received intensive multimodal therapy including craniospinal irradiation and multi-agent chemotherapy. This case highlights the diagnostic value of integrated histopathological and molecular classification in an unusual spinal tumor occurring in an adolescent. In particular, DNA methylation profiling was crucial for confirming the diagnosis and assigning the tumor to the ATRT-MYC subgroup.