Wilms' tumor or Wilms tumor, also known as nephroblastoma, is a cancer of the kidneys that typically occurs in children (rarely in adults), and occurs most commonly as a renal tumor in child patients. It is named after Max Wilms, the German surgeon (1867–1918) who first described it.
Approximately 650 cases are diagnosed in the U.S. annually. The majority of cases occur in children with no associated genetic syndromes; however, a minority of children with Wilms' tumor have a congenital abnormality. It is highly responsive to treatment, with about 90 percent of children being cured.
Signs and symptoms
Typical signs and symptoms of Wilms' tumor include the following: a painless, palpable abdominal mass loss of appetite abdominal pain fever nausea and vomiting blood in the urine (in about 20% of cases) high blood pressure in some cases (especially if synchronous or metachronous bilateral kidney involvement) Rarely as varicocele
Pathogenesis
Wilms' tumor has many causes, which can broadly be categorized as syndromic and non-syndromic. Syndromic causes of Wilms' tumor occur as a result of alterations to genes such as the Wilms Tumor 1 (WT1) or Wilms Tumor 2 (WT2) genes, and the tumor presents with a group of other signs and symptoms. Non-syndromic Wilms' tumor is not associated with other symptoms or pathologies. Many, but not all, cases of Wilms' tumor develop from nephrogenic rests, which are fragments of tissue in or around the kidney that develop before birth and become cancerous after birth. In particular, cases of bilateral Wilms' tumor, as well as cases of Wilms' tumor derived from certain genetic syndromes such as Denys-Drash syndrome, are strongly associated with nephrogenic rests. Most nephroblastomas are on one side of the body only and are found on both sides in less than 5% of cases, although people with Denys-Drash syndrome mostly have bilateral or multiple tumors. They tend to be encapsulated and vascularized tumors that do not cross the midline of the abdomen. In cases of metastasis it is usually to the lung. A rupture of Wilms' tumor puts the patient at risk of bleeding and peritoneal dissemination of the tumor. In such cases, surgical intervention by a surgeon who is experienced in the removal of such a fragile tumor is imperative.
Pathologically, a triphasic nephroblastoma comprises three elements: blastema mesenchyme (stroma) epithelium
Wilms' tumor is a malignant tumor containing metanephric blastema, stromal and epithelial derivatives. Characteristic is the presence of abortive tubules and glomeruli surrounded by a spindled cell stroma. The stroma may include striated muscle, cartilage, bone, fat tissue, and fibrous tissue. Dysfunction is caused when the tumor compresses the normal kidney parenchyma.
The mesenchymal component may include cells showing rhabdomyoid differentiation or malignancy (rhabdomyosarcomatous Wilms).
Wilms' tumors may be separated into two prognostic groups based on pathologic characteristics: Favorable – Contains well developed components mentioned above Anaplastic – Contains diffuse anaplasia (poorly developed cells)
Molecular biology and related conditions
Mutations of the WT1 gene which is located on the short arm of chromosome 11 (11p13) are observed in approximately 20% of Wilms' tumors, the majority of them being inherited from the germline, while a minority are acquired somatic mutations. In addition at least half of the Wilms' tumors with mutations in WT1 also carry acquired somatic mutations in CTNNB1, the gene encoding the proto-oncogene beta-catenin. This latter gene is found on short arm of chromosome 3 (3p22.1).
Most cases do not have mutations in any of these genes.
An association with H19 has been reported. H19 is a long noncoding RNA located on the short arm of chromosome 11 (11p15.5).
Diagnosis
The majority of people with Wilms' tumor present with an asymptomatic abdominal mass which is noticed by a family member or healthcare professional. Renal tumors can also be found during routine screening in children who have known predisposing clinical syndromes. The diagnostic process includes taking a medical history, a physical exam, and a series of tests including blood, urine, and imaging tests.