Mole Blue Nevus
The blue nevus is a solitary, slightly elevated, round, regular nevus, usually less than 0.5 cm. Coloration is attributed to intensely pigmented melanocytes located in the mid to lower dermis. The brown pigment absorbs the longer wavelengths of light and scatters blue light. This is called the Tyndall effect. The blue nevus appears in childhood and is most common on the extremities, head and neck, buttock and dorsum of the hands. A rare variant, the cellular blue nevus, is larger (usually greater than 1 cm) and nodular and is frequently located on the buttock. Melanomas are reported arising in association with a common or cellular blue nevus and arising de novo and resembling cellular blue nevi. Blue nevi may be removed for cosmetic purposes.