Strawberry-shaped birthmarks called infantile hemangiomas grow rapidly in infants much earlier than previously thought, Mayo Clinic and University of California, San Francisco, researchers found. Their study, published online in the journal Pediatrics, suggests that babies with complication-causing hemangiomas should be immediately referred to dermatologists for further evaluation.

Infantile hemangiomas are the most common tumor in infancy. They tend to appear in the first weeks of life and grow as a child ages. Potential complications include permanent disfigurement of the face or functional compromise of vital organs.

"Our goal was to try to figure out when this actual period of rapid growth happened," says Megha Tollefson, M.D., a Mayo Clinic Children's Center researcher and pediatric dermatologist who conducted the study with Ilona Frieden, M.D., of the University of California, San Francisco.

"Then we could potentially intervene if we had to."

The researchers examined photos of 30 infants from birth to 3 months, analyzing the color, thickness and distortion of anatomic landmarks.

Previously, physicians believed that the tumors grew during the first 5 months of life, but researchers had not yet discovered when the most rapid growth took place.

"By using a novel study design, we were able to demonstrate that the period of most rapid hemangioma growth of superficial hemangiomas occurs between 5.5 and 7.5 weeks of age," Dr. Frieden says.

The new findings suggest that infants with high-risk infantile hemangiomas should be seen by a dermatologist as soon as possible, preferably by 4 weeks old. This way therapy, such as drug treatment and laser removal, can start as soon as possible.

"Depending on where the hemangioma is located, it could potentially have long-term impact," Dr. Tollefson says. "We now have the possibility of preventing a lot of that."