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Gastrointestinal stromal tumors: diagnostic challenges and practical approach to differential diagnosis
Richard Kirsch1, Zu-Hua Gao, Robert Riddell
1Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada. rkirsch@mtsinai.on.ca
Abstract:
Over the last decade, gastrointestinal stromal tumors (GISTs) have evolved from histogenetically obscure gastrointestinal mesenchymal tumors to well-defined tumors with distinctive clinical, morphologic, ultrastructural, histogenetic, and molecular characteristics, for which targeted therapy is available. This is largely attributable to the discovery of CD117 overexpression and activating mutations in c-kit or platelet-derived growth factor alpha genes in most of GISTs. The availability of specific diagnostic tests and targeted therapy for GISTs has led to an increased awareness of these tumors. At the same time, the list of potential GIST mimics has lengthened considerably and it has become increasingly important that GISTs be distinguished from their mimics because correct diagnosis has implications for both treatment and prognosis. The purpose of this review is to provide an update of the expanding differential diagnosis of GISTS, to draw attention to unusual GIST variants, to provide a practical approach the differential diagnosis of GISTs and to highlight some of the challenges faced by pathologists in resolving this differential diagnosis.
Insights
Gastrointestinal stromal tumors (GISTs) are now well-defined with targeted therapies, thanks to understanding CD117 and gene mutations. Distinguishing GISTs from mimics is crucial for accurate diagnosis, treatment, and prognosis.
Area of Science:
- Gastroenterology
- Oncology
- Pathology
Background:
- Gastrointestinal stromal tumors (GISTs) have undergone significant evolution in understanding over the past decade.
- Advances include defining their clinical, morphologic, ultrastructural, histogenetic, and molecular characteristics.
- Targeted therapy is now available for GISTs, largely due to the discovery of CD117 overexpression and activating mutations in c-kit or PDGFRA genes.
Purpose of the Study:
- To provide an update on the expanding differential diagnosis of GISTs.
- To highlight unusual GIST variants.
- To offer a practical approach to the differential diagnosis and address challenges faced by pathologists.
Main Methods:
- Review of current literature and diagnostic criteria for GISTs.
- Analysis of characteristic features distinguishing GISTs from mimics.
- Discussion of diagnostic challenges and pitfalls.
Main Results:
- Increased awareness of GISTs due to diagnostic tests and targeted therapy.
- A growing list of potential mimics requires careful differentiation.
- Identification of specific molecular markers (CD117, c-kit, PDGFRA) aids diagnosis.
Conclusions:
- Accurate distinction between GISTs and their mimics is critical for appropriate patient management.
- Pathologists face challenges in resolving the differential diagnosis of GISTs.
- Understanding GIST variants and diagnostic approaches improves patient outcomes.
