KIT XXXX mutation defines a subset of predominantly @entity674 of intestinal origin.

@entity1 @entity5 @entity1320 @entity674 @entity361 @entity70939
@entity674 ( @entity674 ) are the most common @entity361 of the gastrointestinal tract. @entity674 express KIT and show gain-of-function KIT mutations. Most of these mutations affect the KIT juxtamembrane domain, but other KIT domains are mutated at a lower frequency. In this study, frequency of GCC TAT insertion mutation ( @entity70939 ) in KIT exon 9 (extracellular domain) and its possible clinicopathologic significance was investigated. Screening of 520 @entity674 identified 26 cases with @entity70939 KIT mutation and confirmed the previously reported low frequency of this type of KIT mutation among @entity674 of different locations. Of the 26 @entity5 with @entity70939 KIT mutation studied, 21 originated from the small intestine, 1 from the colon, and 3 from the rectum. In 1 case, primary small intestinal versus colonic localization could not be clearly established because of @entity1320 . No distinctive morphological features were identified for the cohort of @entity5 defined by @entity70939 KIT mutations. Most of the @entity5 showed predominant spindle cell morphology, and a few cases had epithelioid or pleomorphic histological features. Following previously published criteria based on @entity5 size and mitotic rate, 22 of 26 (85%) @entity5 were classified as malignant or potentially malignant, and 4 (15%) were classified as probably benign. A malignant clinical course was documented in 18 of 19 @entity5 from the malignant category. The survival times of 11 @entity1 who died of disseminated @entity674 ranged from 1 month to 105 months (median survival time, 26 months). In contrast, 2 of 4 @entity674 assigned as probably @entity5 with follow-up information had long disease-free survival. @entity674 carrying @entity70939 occur exclusively in the intestinal location, and a great majority of these @entity5 follow a malignant course.
