Background: The histogenesis of acquired melanocytic nevi is still a matter of debate.
Objective: To provide data on the histogenesis, we investigated the lesional area of acquired melanocytic nevi and the proliferative activity of the nevus cells.
Methods: Proliferative activity was examined with a monoclonal antibody against proliferating cell nuclear antigen (PCNA). The lesional area of the nevus was estimated in histologic sections.
Results: Intradermal nevus was the largest of the acquired melanocytic nevi but had few PCNA-positive nevus cells. In contrast, junctional nevi were smallest and showed the highest PCNA positivity. Statistical analysis showed a significant inverse correlation between the largest lesional area and PCNA positivity.
Conclusion: The findings of the present study are in accordance with an epidermal melanocytic origin of acquired melanocytic nevi.