Author: Naomi Ashman, Dermoscopist, Torbay Skin, Auckland, New Zealand; DermNet New Zealand Editor in Chief, Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Created February 2019.
A blue naevus is a common type of melanocytic naevus in which the pigment is situated deep in the dermis. It is also known as a blue neuronaevus and a dermal melanocytoma.
A blue naevus is a well-circumscribed round or oval macule, papule or nodule of a uniform steel blue colour. The border fades gradually into the surrounding skin.
In adults, the lesion is often long-standing. The most common age of onset is late childhood or adolescence.
The dermoscopic hallmark of a blue naevus is homogeneous blue pigmentation. In some exceptional cases, they may exhibit blue globules and dots .
Dermoscopic features of a blue naevus are:
The presence of any of the following structures should warrant further investigations for melanoma: network, dots, clods, streaks, vessels, additional colours.
The primary concern of a lesion presenting as a blue naevus with unknown history is that it could be one of the following:
The histological explanation of a blue naevus is:
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