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What is PIK3CA-related overgrowth spectrum (PROS)?

PIK3CA-related overgrowth spectrum (PROS), also known as PIK3CA mutation or PROS syndrome, is a group of rare genetic conditions caused by changes (mutations) in the PIK3CA gene. These conditions lead to abnormal growth of tissues in certain areas of a child’s body. PROS most often affects the skin, bones, blood vessels, and fatty tissue, but it can also affect other parts of the body.

PROS happens because the genetic change affects only some cells in the body, leading to localized overgrowth — tissue that grows larger or develops more than expected in certain areas of the body. PROS is not inherited, and parents do not pass it on to their children.

Symptoms & Causes

What are the symptoms of PIK3CA-related overgrowth spectrum (PROS)?

PROS affects children in different ways, and symptoms vary depending on which parts of the body are affected and how much overgrowth occurs. Common features may include:

  • Uneven or asymmetric growth of one side of the body (localized overgrowth)
  • Differences in arm or leg length (limb length discrepancy)
  • Fingers or toes that grow larger or longer than expected
  • Areas of fatty tissue that grow larger than expected, such as soft lumps under the skin in affected areas of the body, like the arms, legs, and trunk
  • Changes in the skin, such as thickened areas or visible blood vessels
  • Blood vessels that develop differently than usual (vascular malformations or lymphatic malformations), which in some cases may be associated with blood clots
  • Curvature of the spine (scoliosis) or other spinal changes
  • Larger-than-average head size (macrocephaly)
  • Seizures or epilepsy (in some children)
  • Developmental delays or learning differences

Not all children experience the same symptoms, and many children lead active lives with appropriate care.

What causes PIK3CA-related overgrowth spectrum (PROS)?

The PIK3CA gene plays a role in controlling how cells grow and divide. PROS occurs when a somatic mutation — a genetic change that happens in some cells but not others — affects this gene, leading to changes in specific areas of the body. When the gene is altered in certain cells, those cells may grow more than expected, causing localized overgrowth.

Because this type of genetic change affects only some cells and is not inherited, PROS does not usually run in families. This mutation happens by chance and is not the result of anything a parent did or could have prevented.

Diagnosis & Treatments

How is PIK3CA-related overgrowth spectrum (PROS) diagnosed?

Doctors diagnose PROS using a combination of physical exams, imaging studies, and genetic testing. Because the mutation may only be present in affected tissue, genetic testing often requires a sample from the overgrown area rather than a blood test alone.

Diagnosis may take time and may involve more than one test, especially because symptoms can vary widely from child to child.

How is PIK3CA-related overgrowth spectrum (PROS) treated?

There is no single treatment for PIK3CA-related overgrowth spectrum (PROS). Care focuses on managing symptoms, monitoring growth, and supporting a child’s development over time. Treatment plans are tailored to each child and may change as a child grows and their needs evolve. Depending on a child’s specific needs, their care may involve a team of pediatric specialists, such as geneticists, orthopedics and sports medicine surgeons, plastic and oral surgeons, hematologist-oncologists, and clinicians experienced in caring for children with complex medical needs.

PROS management may involve one or more of the following:

  • Monitoring and follow-up care to track growth and changes over time
  • Medications, which in some children may include targeted therapies such as sirolimus or alpelisib to help manage symptoms related to vascular or lymphatic involvement
  • Surgical procedures to address functional, orthopedic, or cosmetic concerns
  • Supportive therapies, such as physical or occupational therapy, when movement or function is affected

Living with PIK3CA-related overgrowth spectrum (PROS)

Living with PROS often involves long-term care and monitoring, especially during periods of growth. Physical symptoms, emotional well-being, and everyday needs can all change over time.

Care teams work closely with families to help children manage physical symptoms, support emotional well-being, and address practical concerns related to daily life as they grow and develop.

When should you contact a health care provider?

If your child is diagnosed with PIK3CA-related overgrowth spectrum (PROS), contact a health care provider if you notice rapid changes in growth, increasing pain, new movement difficulties, or other new or worsening symptoms. Early communication can help guide care and address concerns.

How we care for PIK3CA-related overgrowth spectrum (PROS)

The Vascular Anomalies Center at Boston Children’s Hospital provides care for children whose blood or lymphatic vessels are affected by PROS. Our clinicians diagnose, treat, and provide ongoing care for vascular and lymphatic involvement, working closely with families to develop care plans that may change over time as children grow and develop. We coordinate care with specialists across Boston Children’s, including geneticists, orthopedic surgeons, dermatologists, plastic surgeons, and other pediatric specialists, depending on each child’s individual needs.