Congenital Mesoblastic Nephroma: Causes, Symptoms, and Treatment
Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 2, 2026.
What kind of doctor treats Congenital Mesoblastic Nephroma?
A pediatric nephrologist, who treats kidney problems in children, is often involved in care. A pediatric surgeon or pediatric urologist usually performs the surgery. Many children are treated at centers specializing in childhood tumors, with several specialists working together. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What it is
Congenital mesoblastic nephroma is a rare kidney tumor that is present at birth. It grows in the tissue that supports the kidney, the organ that filters waste from the blood. Doctors consider it the most common kidney tumor found in newborns. Most of these growths are not cancerous in the way adult cancers are, and they rarely spread.
Symptoms
The most common sign is a firm lump in the baby's belly that a parent or doctor can feel. Some babies have high blood pressure, vomiting, poor feeding, or trouble gaining weight. Many babies show no problems at all, and the tumor is often found during a routine exam or a prenatal ultrasound.
Causes and who gets it
Doctors do not fully know what causes congenital mesoblastic nephroma. It happens while the baby is developing in the womb, when certain kidney cells grow the wrong way, and some cases involve gene changes. It is not caused by anything a parent did or did not do. It affects boys slightly more often than girls.
How doctors diagnose it
Diagnosis usually starts with a physical exam, followed by an ultrasound or MRI to picture the kidney. Blood and urine tests can show how well the kidneys are working. The final diagnosis usually comes from examining the removed tumor under a microscope after surgery.
Treatment
Surgery is the main treatment. Surgeons remove the tumor, and sometimes the whole kidney along with it. Most babies do very well because this tumor rarely comes back or spreads, though some may need chemotherapy. Doctors follow up with regular imaging scans, and outcomes are generally good.
When to see a doctor
Parents should contact a doctor if they feel a lump in a baby's belly or notice one side looks larger than the other. Other warning signs include poor feeding, frequent vomiting, or poor weight gain. Any kidney tumor found on a prenatal ultrasound should also be reported. Early evaluation helps doctors plan the safest treatment.
How a direct primary care or concierge doctor fits in
A direct primary care doctor is paid a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. Either type can examine a baby, order imaging tests, and coordinate referrals to a pediatric nephrologist or surgeon. They do not perform this surgery or manage the tumor themselves, so a specialist referral is always needed. After surgery, the primary care doctor can handle routine follow-up and general care alongside the specialists.
Common questions
Is congenital mesoblastic nephroma cancer?
It is a tumor, but it is usually not cancerous in the way many adult tumors are. It rarely spreads, and most children are cured with surgery alone.
Can it be found before birth?
Yes. Some cases are discovered on a routine prenatal ultrasound. Others are found after birth when a doctor feels a lump.
Will my baby need chemotherapy?
Most babies do not need chemotherapy because surgery removes the tumor completely. Doctors may recommend it if the tumor has features that raise the chance of it coming back.
Sources
- NIH Genetic and Rare Diseases Information Center - Congenital mesoblastic nephroma
- MedlinePlus - Kidney Cancer
- National Institute of Diabetes and Digestive and Kidney Diseases - Kidney Disease - NIDDK
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
