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Diagnosis of gastrointestinal stromal tumors from minute specimens: Cytomorphology, immunohistochemistry, and molecular diagnostic findings


  • Lester J. Layfield M.D.,

    Corresponding author
    1. Department of Pathology, University of Utah School of Medicine and ARUP Laboratories, Salt Lake City, Utah
    • Department of Pathology, 1950 Circle of Hope, Rm 6755, Salt Lake City, UT 84112, USA
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  • Michelle L. Wallander Ph.D.

    1. ARUP Institute for Clinical and Experimental Pathology, ARUP Laboratories, Salt Lake City, Utah
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Gastrointestinal stromal tumors (GIST) are the most common mesenchymal neoplasm arising from the gastrointestinal tract. Workup of these lesions includes morphologic study and immunohistochemical and often molecular diagnostic analysis. Historically, these neoplasms had been included under a number of diagnostic categories including leiomyoma, leiomyosarcoma, schwannoma, and leiomyoblastoma. The lesions that were clearly sarcomatous were difficult to treat and therapeutically refractory to chemotherapeutic agents. Significant progress in our understanding of these neoplasms and our ability to successfully treat them occurred following the discovery that they were immunoreactive for KIT protein and harbored activating mutations in the KIT gene. Many are initially diagnosed by fine-needle aspiration (FNA) but workup may include mutational analysis to help direct therapy. This review outlines a practical approach to the cytologic diagnosis of GISTs and their molecular workup on small specimens obtained by FNA or core biopsy. Diagn. Cytopathol. 2012;40:484–490. © 2012 Wiley Periodicals, Inc.