An unusual association of deletion of SMARCB1 in a patient with intracranial yolk sac tumor: A case-report

Deletion of SMARCB1/loss of INI is a well-known association in atypical rhabdoid teratoid tumors (ATRT) in the brain, rhabdoid tumors in the kidney, and less common tumors systemic tumors like sinonasal INI1 deficient carcinoma, gastric undifferentiated carcinoma, undifferentiated uterine sarcomas, and poorly differentiated chordomas. We describe homozygous deletion of the SMARCB1 gene in a patient diagnosed with pineal yolk sac tumor (YST), which is a rare entity. This association highlights the importance of INI1 staining when the clinical course is not progressing as expected and brings us to a critical management question: should this rare entity be treated more aggressively, like ATRT, versus the conventional approach to intracranial YST?