Children rarely get kidney cancer, but when they do, in most cases it is a type of cancer known as Wilms' tumors, or nephroblastomas. These tumors account for 95 percent of child kidney cancers, according to Cancer Research UK. Wilms' tumors usually affect children under the age of 5 but can occur, in rare cases, in older children and adults. The tumors might start to grow while the child is in the womb, but symptoms may appear only after birth.
Swelling and Pain
A swollen abdomen is the most common symptom of Wilms' tumors. A parent may feel a palpable mass or lump in the child's abdomen. The tumors are painless, so the child may never complain of discomfort. The tumors may prove difficult to find in the early stages of the disease and may grow into large masses while causing no pain. The American Cancer Society notes that children may appear healthy while the tumor grows, and parents may only notice the abdominal mass when changing or bathing a child. Sometimes, the first sign of this type of kidney cancer that a parent may notice is a sudden increase in an infant's diaper size. Less commonly, bleeding may occur inside the tumor, and this may cause abdominal pain, notes Cancer Research UK. The pain associated with kidney cancer may occur on the sides or in the back. A child who has a palpable abdominal mass and abdominal pain symptoms requires immediate medical attention.
Blood in the Urine
A child with Wilms' tumors may pass urine that contains blood, a symptom known as hematuria. The urine may appear reddish or pinkish in color. Hematuria symptoms appear in 15 to 20 percent of cases, notes the Merck Manual for Healthcare Professionals. This symptom indicates that the tumor has invaded the kidney's collection system. Blood in the urine may also signal alternate conditions, and a parent should seek medical attention for a child who exhibits this symptom.
Flu-Like Symptoms
Less common symptoms of this type of kidney cancer in children include symptoms resembling those of the flu, including fever, nausea, vomiting and a general feeling of malaise. The Merck Manual mentions that children with Wilms' tumors may experience anorexia---a loss of appetite or an actual dislike for food. These symptoms might lead to weight loss symptoms in the child. If the cancer has metastasized and affected the lungs, symptoms may include coughing and shortness of breath.
