Blue Nevi

Blue nevi are benign lesions that are usually acquired during childhood or adulthood. Only rarely are they present at birth. They are collections of melanocytes, the pigmented cells of the skin. Melanocytes usually migrate to the epidermis (top layer of the skin) during fetal development.

In blue nevi they remain in the dermis (the middle layer of skin). There are several types of blue nevi. The two most common forms are common blue nevi and cellular blue nevi.

All variants of blue nevi usually appear as well-circumscribed, dome-shaped, smooth, blue to blue-gray or blue-black firm bumps (papules or nodules). The blue or gray color appears due to Tindall effect (scattering of light from deep-seated brown pigment). In other words, if the cells composing blue nevi were located more superficially, they would look brown. Since the pigment is located deep in the skin, it appears blue or gray.

Blue nevi are most commonly located on the scalp, sacral region and the tops of the hands and feet. Common blue nevi are usually less than 1.0 cm in diameter. They may occur anywhere, but the majority of these lesions are found on the hands and feet. Cellular blue nevi are usually larger, ranging from 1 to 3 cm in diameter. The majority of cellular blue nevi are located on the buttocks or sacral area.

Blue nevi that are less than 1 cm and are asymptomatic and not changing in size, shape, color or texture can be watched by your dermatologist on a routine basis. Skin biopsy or surgical excision should be performed on multinodular or plaque-like lesions and any lesion that is changing or becomes symptomatic (itching, tenderness, bleeding, etc.).

Gonzalea-Campora R, et al. Blue nevus: classical types and related entities – a differential diagnostic review. Pathol Res Pract 1994;190:627.

Celeste Angel, D.O.
Department of Dermatology
Philadelphia College of Osteopathic Medicine/Frankford Hospital
Philadelphia, Pennsylvania.