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Gastrointestinal Mesenchymal Tumors (gastrointestinal + mesenchymal_tumor)
Selected AbstractsPKC theta, a novel immunohistochemical marker for gastrointestinal stromal tumors (GIST), especially useful for identifying KIT-negative tumorsPATHOLOGY INTERNATIONAL, Issue 3 2005Atsushi Motegi Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor in the digestive tract and the majority of GIST has characteristic gain-of-function mutations of the c-kit gene, which encodes the KIT receptor for stem cell factor. The present study aimed to establish the usefulness of protein kinase C theta (PKC ,) as an immunohistochemical marker for GIST in comparison with KIT immunohistochemistry. PKC , immunohistochemistry was carried out not only on 48 cases of GIST and another 40 cases of gastrointestinal mesenchymal tumors, but also on 24 cases of various tumors known to be immunohistochemically positive for KIT. Immunohistochemically, 41 out of 48 cases (85%) of GIST were positive for PKC ,, and its expression was confirmed by Western blot analysis using six cases of surgically resected GIST. In the present study there were six GIST immunohistochemically negative for KIT, which histologically revealed a myxoid epithelioid appearance characteristic to that of GIST with platelet-derived growth factor receptor alpha mutation. All six GIST were immunohistochemically positive for PKC ,. No PKC , immunoreactivity was observed in other gastrointestinal mesenchymal tumors and various KIT-positive tumors except for three cases (14%) of gastrointestinal schwannomas. The present study revealed that PKC , is an immunohistochemically novel and useful marker for GIST, especially for GIST negative for KIT. [source] Tyrosine kinase mutations in gastrointestinal stromal tumors in a nation-wide study in IcelandAPMIS, Issue 9 2010GEIR TRYGGVASON Tryggvason G, Hilmarsdottir B, Gunnarsson GH, Jónsson JJ, Jónasson JG, Magnússon MK. Tyrosine kinase mutations in gastrointestinal stromal tumors in a nation-wide study in Iceland. APMIS 2010; 118: 648,56. Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. It is characterized by activating mutations in the tyrosine kinase genes c-kit or PDGFRA. This study examined the mutation rate and type in a population-based material. All gastrointestinal mesenchymal tumors over the years 1990,2004 were evaluated and GIST tumors identified using immunohistochemistry (c-kit) and conventional pathologic parameters. Paraffin sections from all tumors were subjected to mutation analysis on exons 9, 11, 13 and 17 of the c-kit gene and exons 12 and 18 of the PDGFRA gene. To screen for mutations, we used a highly sensitive conformation-sensitive gel electrophoresis (CSGE) and to define the mutated alleles, we employed direct automated DNA sequencing. All c-kit-positive gastrointestinal mesenchymal tumors were entered into the study. Fifty-six tumors from 55 patients were analyzed. Mutations were found in 52 tumors representing a 92.9% mutational rate. Most of the mutations were found in c-kit exon 11 (76.8%), followed by c-kit exon 9 (10.7%). PDGFRA mutations were only found in three tumors. No correlation of mutation type with biologic behavior was found. This population-based study, using a sensitive CSGE method, identifies mutations in the great majority of patients with GIST. [source] | ||||||||||