KIT and gastrointestinal stromal tumor: Gastrointestinal stromal tumour (GIST) was historically classified as gastrointestinal leiomyosarcoma before the identification of activating mutations in KIT by Hirota et al (1998) and the immunohistochemical association, with interstitial cells of Cajal by Kindblom and others (Kindblom et al, 1998) in the late 1990s.