Fig 1 Blotch
In our case, the blotch was symmetrically disposed and a peripheral reticular network was visible. This kind of blotch is also called black lamella.
This lesion was corresponding to a benign melanocytic nevus.
It has to be distinguished from the blue structure-less pattern or blue homogeneous pattern of a blue nevus (fig 2).
Fig 2 Blue homogeneous pattern