Junctional Naevus
Author: Dr Olivia Wooler
Chief Editor: Dr Daniel Keith
Junctional naevi are benign proliferations of melanocytes at the dermal-epidermal junction. Most people have multiple, usually appearing in childhood or early adolescence and increasing in number until early adulthood. They present as brown macules that are flat or very slightly elevated from the skin. As they age, they may develop into compound naevi, becoming more papular. Although rare, they do have the potential to transform into malignant melanoma.
Macroscopic Appearance
Junctional naevi are flat or slightly raised pigmented lesions with a round or oval shape. Their colour is uniform and ranges from light to dark brown. They are usually small, often less than 6mm, with well-defined borders and a smooth surface.
Figure 1.
A slightly raised junctional naevus with regular borders and uniform pigmentation.
Figure 2.
A macular junctional naevus. The pigmentation is slightly darker centrally but the colour is symmetrical.
Figure 3.
A junctional naevus with a smooth surface and well defined borders.
Dermoscopic Appearance
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Junctional naevi exhibit a reticular pattern on dermoscopy. This is characterised by a network of intersecting, pigmented lines that resemble a grid.
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The pigmentation is often more prominent in the centre of the lesion and fades towards the periphery.
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Dots and globules may be seen overlying the pigment network.
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Regular blotches, which are areas of heavy pigmentation, may be present and obscure the network pattern. The regular blotches seen in benign naevi display symmetry and are normally located in the centre of the lesion, surrounded by a pigment network. Irregular blotches, associated with dysplastic naevi or melanoma, are asymmetric with irregular borders, often located off-centre and/or display multiple dark hues.
Figure 4.
Dermoscopic appearance of Figure 1. A regular pigment network that fades at the periphery.
Figure 5.
Dermoscopic appearance of Figure 2. Homogenous hyperpigmentation in the centre of the lesion obscures the network. The lines of the network thin and fade at the periphery.
Figure 6.
Annotated (left) and unannotated (top right).
Dermoscopic appearance of Figure 3. In the centre of the lesion there is an uneven distribution of the pigment network, resulting in a patchy appearance.The white area where the network clears (arrow), represents the opening of a hair follicle - this is commonly seen in a benign naevi.