ATRT-04. INHERITED RHABDOID PREDISPOSITION SYNDROME: A CASE OF CHOROID PLEXUS CARCINOMA AND ATYPICAL TERATOID RHABDOID TUMOR IN SIBLINGS

Choroid plexus carcinoma (CPC) and Atypical teratoid/rhabdoid tumor (ATRT) are aggressive, malignant brain cancers most commonly arising in children less than 3 years of age. These tumors often have genetic alterations in the tumor suppressor gene SMARCB1/INI1. Rhabdoid predisposition syndrome (RTPS) categorizes patients with germline mutations in SMARCB1 or SMARCA4, leading to a markedly increased risk of developing rhabdoid tumors. Both CPC and ATRT have been demonstrated in patients with these rhabdoid predisposition syndromes. In general, these tumors tend to have a poor prognosis. However, with the presence of a SMARCB1 mutation they may have improved overall survival. We present two interesting cases of siblings with maternally inherited SMARCB1 mutations: one a 21-month-old male who presented with an ATRT and another a 10 month old female who presented with a CPC. The ATRT was treated as per the Children’s Oncology Group study ACNS0333 with high dose chemotherapy and stem cell rescue as well as cranial radiation. The CPC was treated as per CPT-SIOP 2009 with etoposide, cyclophosphamide and vincristine. Unlike other patients with these aggressive tumors, both of these patients are alive without evidence of disease recurrence 8 and 7 years post therapy, respectively. Additional genomic testing on both tumors is currently pending in order to potentially identify other mutations that may impact survival. These cases further illustrate the similar profile of two very different tumors with improved overall survival that may be secondary to mutations in SMARCB1 in RTPS.