Not all cases keep spreading. There are periods of spreading and periods when it stops. These are called "active" and "stable" phases.
Vitiligo is a condition where periods of pigment loss and periods when the loss stops can alternate. During the active phase, spots increase or enlarge, and during the stable phase, there is little change for a long time. So the accurate answer to the question "Does it spread?" is "It depends on which phase you are in." This distinction is important because the treatment strategy changes completely. In the active phase, the priority is to stop the spreading; in the stable phase, the priority is to restore color or consider surgical treatment.
