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Epidemiology, classification, clinical presentation, prognostic features, and diagnostic work-up of gastrointestinal mesenchymal neoplasms including GIST

Jeffrey Morgan, MD
Chandrajit P Raut, MD, MSc, FACS
Section Editors
Kenneth K Tanabe, MD
Robert Maki, MD, PhD
Alberto S Pappo, MD
Deputy Editor
Diane MF Savarese, MD


Stromal or mesenchymal neoplasms affecting the gastrointestinal (GI) tract typically present as subepithelial neoplasms, and they are divided broadly into two groups. The most common group consists of neoplasms that are collectively referred to as gastrointestinal stromal tumors (GISTs). They are most often located in the stomach and proximal small intestine, but can occur in any portion of the alimentary tract including occasionally in the omentum, mesentery, and peritoneum [1-5]. The current view is that the overwhelming majority of mesenchymal tumors arising in the GI tract fall into the GIST category, and they are identified mainly by expression of KIT protein; as a group, these tumors are more specifically defined by the presence of activating mutations in the KIT or platelet-derived growth factor receptor A (PDGFRA) genes.

A far less common group of mesenchymal GI tract neoplasms is comprised of a spectrum of tumors that are identical to those that might arise in the soft tissues throughout the rest of the body. These include lipomas, liposarcomas, leiomyomas, true leiomyosarcomas, desmoid tumors, schwannomas, and peripheral nerve sheath tumors [6].

The epidemiology, classification, molecular pathogenesis, diagnostic workup of localized GISTs will be reviewed here. Treatment for GISTs, and GI tract leiomyomas and leiomyosarcomas are discussed elsewhere. (See "Local treatment for gastrointestinal stromal tumors, leiomyomas, and leiomyosarcomas of the gastrointestinal tract" and "Tyrosine kinase inhibitor therapy for advanced gastrointestinal stromal tumors" and "Adjuvant and neoadjuvant imatinib for gastrointestinal stromal tumors".)


Despite being the most common nonepithelial benign neoplasm involving the GI tract, mesenchymal tumors are thought to constitute only 1 percent of primary GI cancers [2,3]. However, their true frequency is unknown. Epidemiologic data such as that from National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) program are difficult to interpret since the early definition of so-called "malignant GIST" was derived from criteria published in 1990, at a time before GIST was molecularly characterized [7].

Experience from epidemiologic studies and active GIST therapeutic trials suggest that the annual incidence of GIST in the United States is at least 4000 to 6000 new cases (roughly 7 to 20 cases per million population per year) [7-10]. The most reliable international epidemiologic data are derived from population-based studies that reexamined histologically and immunohistochemically all cases of potential GIST diagnosed between 1983 and 2000 within one province of Sweden [11], between 1990 and 2003 in all of Iceland [12], between 1995 and 2003 in the Netherlands [13], and between 1998 and 2004 in Taiwan [14]. In the Swedish study, 288 of the 1460 cases examined were felt to represent GISTs, for an annual incidence of 14.5 per million population. The Icelandic study reported an incidence of 11 per million population [12].


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Literature review current through: Sep 2016. | This topic last updated: Jul 22, 2016.
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