In a 15-year-old Taiwanese girl, multiple purple punctate lesions arranged in a systematized, segmental pattern had developed since childhood, beginning from the right thigh and gradually progressing upwards to the right buttock, the left side of the abdomen, circumventing to the left side of the back, and extending to the right arm as well as to the posterolateral aspect of the left leg. Histopathological examination showed dilated capillaries in the uppermost part of the dermal papillae characteristic of angioma serpiginosum. The systematized, segmental and asymmetric arrangement of lesions as noted in the present case suggest that angioma serpiginosum reflects genetic mosaicism.