Diagnosis:

Junctional melanocytic naevus.

Comments:

JUNCTIONAL NAEVI:

• Nests ('theques') of naevus cells at the dermoepidermal junction, mostly located at or near tips of rete ridges
• Sometimes associated lentiginous patterns of junctional naevus cells (i.e., arranged as solitary cells rather than producing nests)
• Associated rete ridge elongation and epidermal hyperpigmentation
• No cellular atypia
• Generally no or little mitotitc activity
• A few melanophages in the upper dermis are commonly present
• Usually small lesion (a few mm) except near or in mucous membranes and, occasionally, acral skin
• Most common in young individuals, but may arise later in life, and may persist for many years