Pigmentary demarcation lines: a population survey.

An examination of 380 patients was accomplished in order to determine the frequency of occurrence of pigmentary demarcation lines in an unselected population. Both white and black patients were included in the study, and there was an equal sex distribution. Separation of data by age groups enabled us to determine that the age of onset is in early childhood in the majority of cases. Seventy-nine percent of black female adults have at least one type of pigmentary demarcation line, with types A and B being present in over 50% of the cases. Seventy-five percent of black male patients had at least one pigmentary demarcation line, with type C being most prevalent. Fifteen percent of white female patients had one pigmentary demarcation line. Finally, it was determined that seven of fifty black women (14%) had the new appearance of type B lines with pregnancy.