Malignant rhabdoid tumor of the kidney in a 7-month-old infant: A rare case report with molecular confirmation of SMARCB1 deletion.

Malignant rhabdoid tumor of the kidney (MRTK) is a rare, highly aggressive renal neoplasm predominantly affecting infants, carrying a poor prognosis. We report a 7-month-old female who presented with a 10-day history of painless gross hematuria. Abdominal imaging revealed a large heterogeneous left renal mass without vascular invasion or distant metastases. Left radical nephrectomy with regional lymphadenectomy achieved complete resection (COG Local Stage II, node-negative). Immunohistochemistry demonstrated complete loss of INI1 expression, and next-generation sequencing confirmed a pathogenic SMARCB1 deletion. This case highlights the diagnostic and therapeutic challenges of MRTK in infancy and highlights the indispensable role of molecular confirmation.