Madame Dimanche, often called Widow Sunday, lived in Paris in the early 1800s and became well known because of an extraordinary cutaneous horn that grew from the center of her forehead. The growth began as a small lesion when she was in her mid-70s and slowly lengthened over several years until it reached about 25 centimeters, or roughly 10 inches, curving upward and slightly backward. Cutaneous horns are made of densely compacted keratin, the same material as hair and nails, and while they look dramatic, they are not horns in the animal sense and have no bone inside. In Madame Dimanche’s case, the horn caused social stigma and physical discomfort but surprisingly very little pain. In 1815, surgeon Joseph Souberbielle removed the horn in a relatively straightforward procedure, and contemporary reports note that she recovered well afterward. The specimen was preserved as a medical curiosity and eventually became part of the collection of the Mütter Museum in Philadelphia, where it is displayed today.