Successful treatment of a 4-year-old girl with pure malignant rhabdoid tumor of the bladder: a case report.

Background: Extracranial malignant rhabdoid tumors (eMRTs) are rare, highly aggressive neoplasms, predominantly arising in the kidneys, with bladder involvement being extremely uncommon. Optimal management strategies, particularly bladder-preserving approaches, are not well-established due to the rarity of these cases.

Case description: We report the case of a 4-year-old girl who presented with persistent gross hematuria. Imaging revealed a large bladder mass and histopathological examination confirmed the diagnosis of an extrarenal rhabdoid tumor with loss of SMARCB1 expression. The patient underwent a multimodal treatment approach, including bladder-preserving surgery, 12 cycles of high-dose MRTK-2020 neoadjuvant chemotherapy [comprising actinomycin D, vincristine, doxorubicin, cyclophosphamide (AVDC), ifosfamide, carboplatin, and etoposide (ICE)], followed by adjuvant radiotherapy. Remarkably, the patient achieved complete remission after two cycles of chemotherapy and remained in continuous remission with no evidence of disease at the 15-month follow-up.

Conclusions: This case underscores the diagnostic challenges of malignant rhabdoid tumors (MRTs) in bladder pathologies and highlights the significance of considering such tumors in differential diagnoses. Despite the limited evidence base, bladder-preserving surgeries, when feasible, should be considered and accompanied by adjuvant therapies for optimal outcomes. This case illustrates the potential for successful treatment of pure MRTs of the bladder using a combination of surgery, chemotherapy, and radiotherapy.