Paul Langerhans was born in Berlin, Germany, in 1847, the son of a well-known physician.1 He studied medicine at Friedrich Schiller University of Jena, Jena, Germany, and at the University of Berlin and was a pupil of Rudolph Virchow.1 He made an outstanding contribution to medicine by describing Langerhans cells while he was a 21-year-old undergraduate student.2 Because these branched cells, which were interspersed throughout the epidermis, were demonstrated by a stain for which nervous tissue has a particular affinity, ie, gold chloride, he suggested that they could be intraepidermal receptors of extracutaneous signals to the nervous system.2 Today, the precision of his observation and his description of the cells seem incredible, when his drawings of 1868, which were made with the use of a primitive light microscope, are compared with the reproductions that can now be obtained with immunofluorescence.These cells were an enigma to dermatologists for more than a century before their immunologic function and importance were recognized.3