The JUNCTIONAL NEVUS represents the transition stage of a developing MELANOCYTIC NEVUS, showing characteristic features of both, the LENTIGO SIMPLEX (MELANOCYTIC LENTIGO), and the COMPOUND NEVUS.

The JUNCTIONAL NEVUS has its main cell proliferation activity (increase of cell number) at the so-termed JUNCTION LINE, which separates the EPIDERMIS from the underlying soft-tissue layers of the skin - hence its denomination. This, however, can not be seen with the naked eye - it is a histological finding.

Clinically, the aspect of a JUNCTIONAL NEVUS is that of dark and somewhat irregularly pigmented FLAT skin spot, larger than a LENTIGO SIMPLEX and - often - smaller than a COMPOUND NEVUS. If anything of the lesion can be palpated with closed eyes, it is no longer a JUNCTIONAL NEVUS rather than - already - a COMPOUND NEVUS.

JUNCTIONAL NEVI most often occur during childhood and adolescence. They are rarely to be found in elder individuals (40+), in which age bracket they would always require further analysis (epiluminescence microscopy, dermatoscopy, dermoscopy).

JUNCTIONAL NEVI are developing MELANOCYTIC NEVI "under construction". They thus will most likely change their aspects over time, eventually unveiling their true nature of a COMPOUND NEVUS. Unfortunately, the same dynamics apply to melanomas in their early development stages likewise. To rule out an early melanoma "under construction", it is recommended to let a dermatologist check these lesions with the use of additional investigative procedures (epiluminescence microscopy, dermatoscopy, dermoscopy). If in doubt, the lesion should be removed by excisional biopsy and histologically clarified.