Blue Naevus
Author: Dr Olivia Wooler
Chief Editor: Dr Daniel Keith
Blue naevi are benign proliferations of dermal melanocytes that typically become apparent in childhood and early adolescence. Once blue naevi appear they tend to remain unchanged throughout life.
Macroscopic Appearance
Common blue naevi present as a well-defined, round or oval macule or papule with a predominantly steel-blue colour. Lesions are usually solitary, less than 1cm, and most commonly arise on the distal extremities, face, or scalp, but can be found anywhere in the body.
Dermoscopic Appearance
The dermoscopic hallmark of blue naevi is structureless blue pigmentation. However, this is a non-specific feature that can also be seen in some melanomas.
The diagnosis of blue naevus should be based on structureless blue pigmentation AND a history of a stable lesion, which has been present without change for several years. If there is any uncertainty about the length of time, it must be treated as a melanoma and surgically removed.
The dermoscopic features of blue naevi are:
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Homogenous blue colour or combination of two colours (white-blue, blue-grey, blue-brown or blue-black)
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The absence of a pigment network
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A well-defined border that fades into the surrounding skin
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A diffuse blue-white veil appearance over the entire surface
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Lack of any other structures, such as networks, dots, streaks or vessels.
Figure 1:
Dermoscopic appearance of blue naevus, demonstrating structurelessblue pigmentation that fades towards theperiphery. White areas represent fibrosis,a relatively common feature of blue naevi.