ABSTRACT
The periungual fibromas in tuberous sclerosis are also known as Koenen tumors. Joannes Henricus Maria Koenen was born on March 10, 1893, in Eindhoven and died in Bois-le-Duc May 29, 1956. From 1910 to 1918 he studied medicine at the University of Amsterdam. Then he worked as a physician at the "Coude-water" asylum in Rosmalen and from 1929 in the "Voorburg" asylum in Vught. In 1932 he published his publication concerning a family with tuberous sclerosis in which photographs of periungual fibromas are shown. His thesis in 1933 at the University in Leiden was titled "Imbecility in children. Its Importance in pedagogic and social regard, by reason of an investigation in some communities in Noord-Brabant". Later he was appointed director of a state mental institution. The periungual fibromas in tuberous sclerosis were first described by Richad Kothe in Munich in 1903.
