Letterer, Erich (1895–1982), German physician. Letterer first described Letterer-Siwe disease in 1924. The author of several textbooks on pathology, he described the disease from the viewpoint of a pathologist.
Siwe, Sture August (1897–1966), Swedish pediatrician. Siwe presented another, independent description of Letterer-Siwe disease in 1933, this time from the clinical point of view.