Malignant rhabdoid tumor of the kidney
Malignant rhabdoid tumor of the kidney (MRTK) is an aggressive and rare cancer primarily affecting infants and young children, with very few cases reported in adults. This cancer is characterized by the presence of rhabdoid cells, which can arise from various types of tissue including epithelial and neural cells. The majority of cases involve a mutation or deletion of the SMARCB1 gene, although no specific risk factors for developing this tumor have been identified. Clinically, symptoms may include fever, blood in the urine, abdominal pain, and hypertension, with potential neurological signs if metastasis occurs. Diagnosis typically involves imaging studies like ultrasound and CT scans, along with genetic testing to confirm mutations. Treatment primarily consists of surgical removal of the affected kidney, often followed by chemotherapy, as well as potential stem cell transplantation. Unfortunately, the prognosis for MRTK is poor, with a significant percentage of patients not surviving beyond eighteen months post-diagnosis. There are currently no known preventative measures for this condition.
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Malignant rhabdoid tumor of the kidney
ALSO KNOWN AS: MRT, MRTK, Rhabdoid tumor of the kidney, atypical teratoid rhabdoid tumor (ATRT)
RELATED CONDITIONS: Wilms’ tumor
DEFINITION: Malignant rhabdoid tumor of the kidney is an extremely aggressive and lethal cancer that occurs primarily in infants and young children, with adult cases being extremely rare.
Risk factors: Malignant rhabdoid tumors of the kidney are caused by a mutation or deletion of the SMARCB1 gene (also called INI1, SNF5, and BAF47) and sometimes the MARCA4 gene. However, there are no known risk factors associated with its development.
Etiology and the disease process: Malignant rhabdoid tumors of the kidney are made up of an overgrowth of rhabdoid (rod-shaped) cells. These cells may appear as epithelial (skin), neural (nerve), muscle, or mesenchymal (rare soft-tissue tumor) cells. A single rhabdoid tumor may include all these types of cells or only one or two. The cells tend to infiltrate the kidney tissue and metastasize early, often in the brain.
Incidence: Malignant rhabdoid tumor of the kidney is rare. Less than 2 percent of cases of childhood renal tumors are malignant rhabdoid tumors, occurring in less than one in one million people. Around 20 cases are diagnosed annually in the United States. Malignant rhabdoid tumors are equally common in both sexes. They are most commonly diagnosed in children between eleven and eighteen months.
Symptoms: The most common symptoms are fever, gross hematuria (blood in the urine), fussiness, abdominal pain, and hypertension. Other symptoms of brain metastasis include seizures and loss of previously achieved motor skills.
Screening and diagnosis: There is no routine screening for malignant rhabdoid kidney tumors. The most definitive testing includes abdominal ultrasound, lumbar puncture, and abdominal computed tomography (CT) scan. A complete blood cell (CBC) count and uranalysis are helpful because about half of MRTK cases present with low hemoglobin levels, and about 75 percent of patients have hematuria in their urine. After these tests, the tumor is biopsied and tested for mutations in the SMARCB1 and SMARCA4 genes.
The staging for malignant rhabdoid tumors of the kidney was devised by the NWTS group and then modified by the Children’s Oncology Group (COG). The stages are as follows:
- Stage I: The tumor has not spread beyond the one kidney.
- Stage II: The tumor is localized to the area around the kidney, and there is no evidence of tumor spread.
- Stage III: The tumor has spread into the abdomen.
- Stage IV: There are metastases outside the abdominal or pelvic cavities.
- Stage V: There are bilateral tumors.
Treatment and therapy: The primary treatment is surgical removal of the kidney. It is usually removed through direct incision to avoid any spillage of cancer cells. At this time, lymph nodes are sampled, and the adrenal gland may be removed. Bilateral tumors are not removed. Chemotherapy is performed on all patients with malignant rhabdoid tumors of the kidney. Stem cell transplantation is also common.
Prognosis, prevention, and outcomes: The prognosis for malignant rhabdoid tumors of the kidney is poor, with about 80 percent of patients dying within eighteen months of diagnosis. Infants under six months have the most grim prognosis, but the five-year survival rate of all individuals is nearly zero. There is no way to prevent it.
Bibliography
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Libertino, John A. Renal Cancer: Contemporary Management. 2nd ed., Spring, 2020.
"Rhabdoid Tumor." Cleveland Clinic, 11 Nov. 2022, my.clevelandclinic.org/health/diseases/24440-rhabdoid-tumor. Accessed 20 June 2024.
Stadler, Walter Michael. Renal Cancer. Demos Medical, 2011.
Zhanghuang, C., et al. "Clinical and Prognostic Analysis of 42 Children with Malignant Rhabdoid Tumor of the Kidney: A 7-year Retrospective Multi-center Study." BMC Pediatrics, vol. 22, no. 591, 2022. doi.org/10.1186/s12887-022-03643-1.