Siegfried Oberndorfer: a tribute to his work and life between Munich, Kiel, Geneva, and Istanbul.

In 1907 Siegfried Oberndorfer published his observations and interpretations on tumorlets ("Geschwulstchen") in the small intestine, which he called carcinoids ("karzinoide Tumoren"). This article pursues the questions why this discovery was so unique and what role it played in the later life of Siegfried Oberndorfer.