Malignant Rhabdoid Tumor of the Kidney and Spine in an Infant
An 8-month-old girl without specific past medical history was admitted to the hospital due to nausea and diarrhea. On physical examination, a firm mass was detected in the left upper quadrant of the abdomen. Abdominal computed tomography (CT) revealed a 6.8×5.8×5.3 cm sized left renal mass without lymph node enlargement (). There were no suspicious metastatic lesions in chest CT. Laboratory data showed leukocytosis. Radical nephrectomy with lymph nodes dissection was performed. Gross examination revealed a well circumscribed, ovoid, firm mass in the lower pole of the kidney (). The mass was abutted on the renal capsule, and the surface of the mass was whitish gray with multifocal hemorrhages. The remaining renal parenchyma was unremarkable. Microscopic findings revealed that the tumor was a highly cellular neoplasm composed of tumor cells of varying size with prominent nucleoli and abundant cytoplasm (). Histological examination was consistent with the diagnosis of malignant rhabdoid tumor. Immunohistochemistry showed loss of INI1 protein staining ().\nOne week after the operation, weakness of both lower extremities and voiding failure were noted. On neurological examination, she failed to respond to pain in both legs. Brain magnetic resonance imaging (MRI) did not show evidence of metastatic disease, but lumbar MRI revealed a 6.5×1 cm sized intradural extramedullary tubular mass with heterogeneous enhancement at L1-S1 level (). On the next day from onset of symptoms, laminoplastic laminotomy was performed by a neurosurgeon to remove the tumor and decompress spinal cord. Conus medullaris was displaced by the hypervascular tumor with yellowish color, however the upper margin of the tumor was clear (). The tumor was densely adhered to the left side of L5 nerve root. Near total removal of the tumor was performed using cavitron ultrasonic surgical aspirator, and there was no root injury during the surgery (). The pathologic findings were consistent with metastatic malignant rhabdoid tumor (). After the surgery, the motor power of lower extremity was returned. She received adjuvant radiotherapy for 2 weeks and 13 cycles of chemotherapy (vincristine, doxorubicin, and cyclophosphamide) for 3 months postoperatively. The patient showed general weakness, seizure and changes in mental status during the chemotherapy. Leptomeningeal metastasis with hydrocephalus was noted in brain MRI. A ventriculoperitoneal shunt was placed. However, she did not clinically improve and died 6 months after the surgery.