Dermoscopy insights into nevogenesis: "Abtropfung" vs "Hochsteigerung"

Two concepts, the “Abtropfung” and the “Hochsteigerung,” have been used to explain the natural evolution of melanocytic nevi. The nevi in Figure 1 and Figure 2 are located on the respective backs of a 25- and a 20-year-old woman. By dermoscopy, the former first exhibited a central bluish pigmentation indicating pigmented cells in the papillary dermis (Figure 1A), while a significant color change toward brown occurred after 8 months (Figure 1B), reflecting the presence of pigment at the dermoepidermal junction. The nevus in Figure 2 reveals an opposite trend after 1 year of follow-up, with significant change of the color from brown (Figure 2A) to blue (Figure 2B). Whether this is caused by a real movement of cells (upward or downward) or by a different activation and/or maturation level of melanin-producing melanocytes remains speculative. Based on our observation, currently both concepts or the concept of “nevus activation” seem to be plausible to explain some steps in the evolution process of melanocytic nevi.