True about GIST all except

.GIST (Gastrointestinal stromal tumour) is rare but most common non epithelial small bowel tumours. * 25% of GIST occurs in small bowel (stomach - 50 to 60%). It is 0.2% of all GI tumours. * It is equal in both sexes * It arises from interstitial cell of Cajal. * More than 95% show c-kit (transmembrane receptor tyrosine kinase) mutation. * Many mesenchymal tumours of small bowel are now classified as GIST. GIST attains massive size when presenting clinically. * Palpable mass, compression, haemorrhage are the features. * CT is diagnostic. ref:SRB&;s manual of surgery,ed 3,pg no 812