A mole (nevus) is a common type of skin growth formed when melanocytes, the pigment-producing cells, cluster together instead of distributing evenly throughout the skin. While most people develop multiple moles throughout their lifetime, marks appearing on a baby often concern parents. Understanding the different types of moles and other benign skin spots that occur in infancy provides clarity regarding these skin changes.
Moles Present at Birth
Babies can be born with moles, known as Congenital Melanocytic Nevi (CMN). This type of mole is present at birth or appears within the first few weeks of life, occurring in approximately 1% to 2% of newborns globally. CMN vary considerably, ranging from light tan to dark black patches or plaques on the skin.
The texture of a congenital nevus can be smooth and flat, or raised, bumpy, or velvety. CMN often feature increased hair growth (hypertrichosis). CMN are classified by size for monitoring purposes. Small CMN are typically less than 1.5 centimeters in diameter, while medium nevi range between 1.5 and 20 centimeters. Larger lesions, sometimes called giant CMN, exceed 20 centimeters in projected adult diameter and are associated with a greater, though rare, risk of complications. These moles grow proportionally with the child’s body size.
Moles That Develop After Infancy
The majority of moles, known as acquired nevi, develop after a baby’s first birthday and throughout childhood and adolescence. While uncommon during the first year of life, their appearance becomes frequent starting in early childhood. Most people accumulate between 10 and 40 common moles by the time they reach adulthood.
These acquired spots typically appear as small, round growths with uniform color, ranging from pink or tan to various shades of brown. Their development is influenced by genetic factors and cumulative exposure to ultraviolet radiation from the sun.
As the skin grows during childhood, it is normal for these new moles to slowly change appearance. They may start as flat spots (junctional nevi) and gradually become slightly raised or dome-shaped (compound or dermal nevi) over several years. This slow, symmetrical evolution is a normal part of the mole’s life cycle and does not indicate a health concern.
Differentiating Moles from Other Common Birthmarks
Parents often confuse moles with other non-nevus birthmarks. One common type is the café-au-lait spot, which translates to “coffee with milk.” It presents as a flat, light-brown patch with a distinct, smooth border. These spots are an overgrowth of pigment cells, but unlike moles, they are flat and uniform in color and texture.
Another frequent pigmented mark, especially in babies with darker skin tones, is the Mongolian spot (congenital dermal melanocytosis). These are flat, bluish-gray patches commonly found on the lower back and buttocks. Mongolian spots result from pigment cells trapped deep in the skin layers and almost always fade completely by early childhood.
Vascular birthmarks involve blood vessels rather than pigment cells and are often mistaken for moles. For instance, a hemangioma, sometimes called a strawberry mark, is a raised, bright-red growth that usually appears a few weeks after birth. It grows rapidly before shrinking. These are soft, compressible masses of blood vessels that are visibly red or pink, unlike the brown or black color of a mole.
Salmon patches, often called stork bites or angel kisses, are flat, pale pink or reddish marks caused by dilated capillaries. These marks are commonly found on the eyelids, forehead, or the back of the neck. They are distinct because they blanch, or temporarily turn white, when gently pressed. Salmon patches on the face typically fade away within the first couple of years of life.
Monitoring Moles and Warning Signs
Most moles, both congenital and acquired, remain harmless throughout a child’s life, but monitoring them is necessary. Any rapid or noticeable change in a mole warrants a consultation with a pediatrician or dermatologist. For congenital nevi, concerning signs include any area that begins to bleed, crust, or develop new, hard bumps within the mole itself.
The general ABCDE criteria used for adults is often modified for children, as pediatric melanomas can present differently. The most important factor for parents to observe is the “E” for evolution, meaning any change in size, shape, color, or texture over a short period. A mole that begins to itch persistently or becomes painful should also be evaluated promptly.
Large CMN (over 20 centimeters projected adult size) carry an elevated lifetime risk of developing melanoma, requiring lifelong monitoring by a specialist. Physicians may also look for the “ugly duckling” sign—a mole that looks distinctly different from all the other moles on the child’s body. While most changes in childhood moles are benign, a medical evaluation is the safest course of action for any rapidly changing or symptomatic mark.