At the Seventh Congress of the German Dermatological Society held in 1901Blaschko presented observations of a rare dermatological condition involving patterned skin lesions S-shaped on the abdomen, V-shaped over the upper spinal region with an inverted U-shape from the breast onto the upper arm. Blaschko based his findings on examinations of over 140 patients with nevoid and acquired linear skin diseases. This unusual patterned condition was later referred to as "lines of Blaschko". Blaschko proposed an embryonic origin for this phenomenon.

Digital facsimile from the Internet Archive at this link.