Loss of neurofibromin activates RAS kinases and downstream kinases, including the MEK-MAPK pathway, and the subsequent expression of ETS Variant Transcription Factor 1 (ETV1), which is an E twenty-six (ETS) family transcription factor expressed in both imatinib-sensitive and imatinib-resistant GISTs required for GIST growth and survival, is a master regulator of an interstitial cell of Cajal (ICC)-GIST-specific transcription network and may induce KIT expression in NF1-associated GISTs [20, 27, 28]; this was seen in the immunostaining results in the present case. The gene discussed is ETV1; the disease is intrahepatic cholangiocarcinoma.