Birth Nevus and Pigmentation

Birth nevus, commonly known as a congenital melanocytic nevus (CMN), is a type of pigmented skin lesion that is present at birth or appears shortly thereafter. These nevi are composed of melanocytes, the pigment-producing cells of the skin, and can vary in size, shape, and color. Congenital melanocytic nevi can range from small, flat lesions to large, raised or hairy moles.

• Characteristics: Congenital melanocytic nevi can vary widely in appearance. They may be tan, brown, or black in color and may have a smooth or irregular surface. The size of the nevus can also vary, ranging from less than 1 centimeter to more than 20 centimeters in diameter. Some nevi may have hair growth (hypertrichosis) or develop nodules or bumps over time.
• Diagnosis: Diagnosis of congenital melanocytic nevi is typically based on clinical examination. Dermatologists or pediatricians may evaluate the size, color, and texture of the lesion and assess for any signs of atypical features that may warrant further evaluation or monitoring. In some cases, a biopsy may be performed to confirm the diagnosis or rule out other skin conditions.
• Risk Factors: While most congenital melanocytic nevi are benign and do not cause medical problems, larger nevi (>20 cm in diameter) have a slightly increased risk of developing into melanoma, a type of skin cancer. The risk of melanoma is higher in individuals with giant congenital melanocytic nevi (GCMN), which are nevi that cover a large area of the body.
• Treatment: Treatment options for congenital melanocytic nevi depend on factors such as the size, location, and cosmetic concerns associated with the lesion. Small nevi that are not causing medical problems may be observed without intervention. Larger nevi or those with cosmetic concerns may be treated with surgical excision, laser therapy, or other techniques to improve the appearance of the skin.