Bessel's disease-the first report of an IgG4-related disorder.

Many aspects of IgG4-related diseases were initially described during the late 19th and early 20th century. A variety of clinical presentations caused by this common pathology have been named after the researchers who first described the disorders, such as Mikulicz, Küttner, Riedel or Ormond. However, the initial description of retroperitoneal fibrosis dates back to even 50 years earlier, when in 1846, the Prussian private practitioner Raphael Jakob Kosch described a hitherto unknown constellation of symptoms and pathological findings in a famous patient. This celebrity was the mathematician and astronomer Friedrich Wilhelm Bessel, a close friend of Alexander von Humboldt and Carl Friedrich Gauss.