A 3-year-old boy is brought to the clinic for evaluation of red-tinged urine, which his mother noticed earlier this week. The patient has had multiple episodes since but has no associated dysuria. He has had no prior injury but was recently treated with antibiotics for streptococcal pharyngitis. The patient has no chronic medical conditions and has reached all developmental milestones. Temperature is 36.7 C (98.1 F). Examination shows a well-appearing and well-nourished boy. There is a firm, nontender, palpable mass in the left abdomen. Urinalysis reveals:
| Blood | 2+ |
| Glucose | negative |
| Protein | negative |
| Bacteria | none |
| Red blood cells | 30/hpf |
| White blood cells | 1/hpf |
Which of the following is the most likely diagnosis for this patient?
Wilms tumor (nephroblastoma) | |
Epidemiology |
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Clinical features |
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Treatment |
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Prognosis |
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Wilms tumor (nephroblastoma) is the most common renal malignancy in children. It is usually diagnosed at age 2-5 and affects one kidney.
Wilms tumors often grow large before they are diagnosed and typically present with an asymptomatic abdominal mass, which may be found incidentally by a caretaker or physician. Hematuria (as in this patient) occurs in up to 25% of those who have Wilms tumors. Other symptoms can include abdominal pain, hypertension, and fever. Although the lungs are the most common site of metastatic spread, children rarely have pulmonary symptoms.
Abdominal ultrasonography is the first step in imaging to differentiate Wilms tumor from other abdominal masses. Subsequently, contrast-enhanced CT or MRI is needed to evaluate the extent of the mass. A CT scan of the chest is also recommended to identify pulmonary metastases. Treatment includes surgery and chemotherapy as well as radiation therapy for late-stage disease. Survival rates are excellent (90%), especially for patients who are treated in the early stages.
(Choice A) IgA nephropathy typically presents with hematuria during an upper respiratory infection. This glomerulonephritis is not associated with tumor development.
(Choice B) Nephrolithiasis (kidney stones) can cause hematuria but is usually very painful. Even large staghorn calculi would present with urinary tract infection and pain rather than an abdominal mass.
(Choice C) Neuroblastoma is a tumor that can arise anywhere in the sympathetic nervous system but typically involves the adrenal glands and presents as an abdominal mass. It is less likely in this patient because it usually affects children age <2 and does not cause hematuria.
(Choice D) Poststreptococcal glomerulonephritis (PSGN) can develop weeks after a group A streptococcal infection (even if treated). Although PSGN is a common cause of nephritis and can present with hematuria, it would not cause a firm abdominal mass and it is commonly associated with edema, hypertension, and (nonnephrotic range) proteinuria.
(Choice E) Renal cell carcinoma is a renal malignancy that presents with flank pain, hematuria, and a mass. However, it occurs predominantly in men age 50-80 and is very rare in young children.
Educational objective:
Wilms tumor is the most common renal malignancy in children. Although it usually presents as an asymptomatic abdominal mass, hematuria may occur in up to one-fourth of patients. Abdominal pain and hypertension may also be present.