Under the dermatoscope, you see the pattern shown in the insert.
This is an unusual picture, but then the patient volunteers that she has recently had intense pulsed light (IPL) hair removal and that the pattern appeared shortly afterwards.
The penny drops!
The power settings used have been set too high for her darker skin type and the light has damaged the melanocytes in the skin, as well as the pigmented hair follicles.
The problem should slowly resolve.