Birthmarks refer to abnormalities in skin color or texture that are present at birth or appear shortly after birth. Vascular birthmarks are comprised of abnormal blood vessels within or just below the skin, and fall into two main categories: hemangiomas and vascular malformations. Hemangiomas contain proliferating capillaries that multiply and grow during the first 6 to 12 months of life. They then slowly regress over an average of 5 years, and the majority is followed conservatively by pediatricians.

Problematic hemangiomas, particularly those involving the airway or eye region, require urgent attention and may require referral to a pediatric dermatologist, plastic surgeon, otolaryngologist, ophthalmologist, or oculoplastic surgeon. Vascular malformations range from innocuous patches of pink pigmentation in the central forehead and back of the scalp (stork bite, or angel's kiss) which tend to fade with time, to persistent patches of pink or purple pigmentation (port wine stains, or capillary vascular malformations), venous malformations, lymphatic malformations, or arteriovenous malformations. Unlike hemangiomas, vascular malformations do not regress with time and can present lifelong functional or psychosocial problems.

A cluster of pigmented cells containing melanin characterizes a congenital mole, or nevus. Most congenital nevi are brown, although some appear bluer in color. They may be tiny, measured in millimeters, or they may cover large body areas such as the entire trunk or extremity. As its name implies, a hairy nevus has associated hair growth. The presence of hair may make a nevus more noticeable, but it does not increase its risk of melanoma transformation.
Types of congenital nevi include:

Congenital Melanocytic Nevus:

• Tan or brown in pigmentation
• May be flat or slightly raised
• Diameter ranges from millimeters to centimeters
• May have associated hair growth
• Risk of melanoma transformation is <1%, and is extremely rare prior to age 11
• Excision is elective, but changing nevi require biopsy to rule out melanoma

Dysplastic Nevus:

• Tan or brown in pigmentation, often variable in color
• Borders are usually fuzzy and irregular
• Microscopic examination reveals atypical pigmented nevus cells
• Increased risk of melanoma transformation
• Patients with a family history of melanoma and dysplastic nevi are at extremely high risk for melanoma and require close follow up every 6 months

Spitz Nevus:

• Tan or pink in pigmentation
• May exhibit rapid growth
• Microscopically may resemble melanoma, hence its misleading nickname "juvenile melanoma", but is benign in nature
• Excisional biopsy provides adequate treatment

Giant Hairy Nevus:

• Usually brown to dark brown in pigmentation
• Large surface area may involve scalp, face, trunk, or extremity
• May develop nodules which warrant biopsy
• Risk of melanoma transformation is 10-15%, and can occur in childhood
• Treatment ranges from conservative observation with biopsy of suspicious areas to staged excision, often involving the use of skin balloon expanders or skin grafts

Nevus Sebaceous of Jadassohn:

• Light tan in pigmentation
• Raised cobblestone texture
• Sebaceous gland stimulation during puberty often leads to a crusted, oily appearance
• 15% risk of basal cell carcinoma transformation warrants removal during childhood

Mongolian Spot:

• Brown to grayish blue in pigmentation
• Composed of melanocytes located in the dermis layer of the skin
• flat in texture, occurring in the buttock, sacral region
• Usually disappears during childhood

Nevus of Ota:

• A Mongolian spot that occurs in the facial area, involving the eye region
• Rarely can transform to melanoma, most commonly in the iris

Nevus of Ito:

• A Mongolian spot that occurs in the shoulder region

Epidermal Nevus:

• Raised tan to brown patches located in the superficial skin layer
• Strong tendency to develop verrucous texture resembling warts
• No melanoma risk, but appearance can be psychologically distressing
• Treatment ranges from dermabrasion, shave excision, laser vaporization to complete excision depending upon location and size