c-KIT gene mutation and clonal origin of multiple gastrointestinal stromal tumors occurring in the peritoneum.
ABSTRACT The present study investigated multiple extragastrointestinal stromal tumors (EGISTs) occurring in the peritoneum, identified their clinicopathologic and immunohistochemical features, and examined their c-KIT gene mutations, clonal status and clonal relationships. Fifteen different tumors of a multiple EGIST from the same female patient were examined by microscopy and immunohistochemistry, then genomic DNA was isolated from the lesions and, as the control, the surrounding fibrous connective tissues. PCR amplification and sequencing were used to investigate the mutation status of c-KIT gene exons 9, 11, 13 and 17. Finally, a clonality assay was conducted based on X-chromosome inactivation mosaicism in female somatic tissues and polymorphisms of the phosphoglycerate kinase and androgen receptor genes. Immunohistochemical analysis revealed CD117- and CD34-positive reactivity in the tumors. Mutation analysis identified the c-KIT gene mutation in exon 13. The clonality assay revealed a loss of X-chromosome inactivation mosaicism and an identical inactivated allele in all 15 nodules. No similar findings were observed in the surrounding fibrous connective tissues. The c-KIT gene mutation was found in the multiple EGISTs from the patient. The EGIST, like most tumors, was of monoclonal origin. This and the identical inactivated allele found in the nodules indicated a common clonal origin for the tumor.
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ABSTRACT: Gastrointestinal stromal tumours (GISTs) are thought to arise from the interstitial cells of Cajal (ICCs). ICCs form a network surrounding the myenteric plexus and between-muscle fibres of the muscularis propria of the tubular GI tract. The cell of origin of so-called extra-gastrointestinal stromal tumours (EGISTs) is not known. To study the diversity of gross presentation of GISTs and to critically assess the incidence of EGISTs and their relationship to mural GISTs, a total of 200 neoplasms with typical morphologic and immunohistochemical features of GISTs were reviewed, looking for any degree of association with the muscularis propria of the gut wall. There were 130 gastric (65%), 9 duodenal (4.5%), 48 small intestinal (24%), 9 colorectal (4.5%), 1 appendiceal (0.5%) and 3 unclassifiable GISTs (1.5%). Fourteen cases (7%) were initially submitted as EGISTs (four mesenteric, four omental, one pararectal/prostatic, one pelvic/Douglas, one perivesical, one located between root of mesentery and tail of pancreas, one involving the mesentery, omentum and abdominal wall extensively and one located between liver and stomach). After critical re-evaluation of surgical reports and remote clinical history and a careful search for residual muscular tissue from the gut wall in the tumour pseudocapsule (in some cases supported by desmin immunoreactivity), it was possible to reclassify most of these cases (11/14) as either GISTs with extensive extramural growth resulting in loss of contact to the external muscle coat of the gut (8/14) or as metastases from an inoperable GIST (2/14) or from a previously resected deceptively benign tumour (1/14). EGISTs are probably rarer than previously reported (1.5% or less in this study). We concluded that most so-called EGISTs represent apparent EGISTs that should have arisen from the outermost muscle coat, but have lost their contact to the point of origin due to extensive extramural growth pattern. From a surgical point of view, it is crucial to document and mark any focal attachment or adhesions to the gut wall noticed during surgery for an apparent EGIST. In contrast to most other neoplasms, GISTs should be defined by virtue of any degree of association with the muscularis propria (no matter how minimal), but not by localisation of the bulk of the tumour.Langenbeck s Archives of Surgery 09/2006; 391(4):322-9. · 2.16 Impact Factor
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ABSTRACT: Diffuse proliferation of interstitial cells of Cajal (ICCs) in the myenteric plexus layer of the intestine has been described in patients with familial and multiple gastrointestinal stromal tumours (GISTs). However, it is not fully understood whether proliferation is polyclonal or monoclonal. To evaluate the clonal nature of diffuse ICC proliferation in familial and multiple GIST cases, we carried out clonal analysis using inactivation at the human androgen receptor (HUMARA) locus. Diffuse ICC proliferation tissues from three female patients were microdissected using a laser capture microdissection (LCM) system. Normal intestinal mucosal tissues were also microdissected for polyclonal controls and GIST tissues for monoclonal controls from the same patients, and genomic DNA was extracted. After digestion by restriction enzyme HhaI, the HUMARA locus was amplified by a fluorescent polymerase chain reaction (PCR) procedure and the PCR products were analysed. One case was uninformative because it was homozygous at the HUMARA locus. In the two other cases, PCR products from the diffuse ICC proliferation showed two alleles as well as those from normal intestinal mucosal tissues, indicating that ICC proliferation was polyclonal. In contrast, PCR products from associated GIST tissues showed only one allele, indicating that GISTs were monoclonal. The results suggested that diffuse ICC proliferation in familial and multiple GIST cases was non-neoplastic hyperplasia.Gut 01/2003; 51(6):793-6. · 13.32 Impact Factor
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ABSTRACT: Gastrointestinal stromal tumors (GISTs) are mesenchymal neoplasms of the gut wall that express the receptor tyrosine kinase KIT. Somatic mutations that result in constitutive activation of KIT kinase have been identified in a number of studies of GISTs, although the reported frequency of these mutations has varied over a wide range (20 to 92%). Several reports have suggested that KIT gene mutations are more common in malignant GISTs than in benign lesions, and it has been proposed that mutations in exon 11 of KIT are a negative prognostic factor. To maximize sensitivity for KIT mutations we have adapted denaturing high-pressure liquid chromatography as a method for screening polymerase chain reaction amplimers of exons 9, 11, 13, and 17 from GIST genomic DNA. This approach was used to assess the frequency of KIT mutations in 13 morphologically benign, incidentally discovered, GISTs identified at autopsy, endoscopy, or laparotomy for unrelated disease. Representing the smallest pathologically recognizable GISTs, these lesions ranged in size from 4 to 10 mm in diameter and were all immunohistochemically positive for KIT. Eleven of the 13 tumors had sequence-confirmed mutations in KIT, including 10 mutations in exon 11 (77%) and one mutation in exon 9 (7.7%). The remaining two tumors were wild type for exons 9, 11, and 17; one of these was also analyzed for exon 13 and was wild type in this exon as well. The mutations found in the incidental GISTs were identical to those that have been documented in larger GISTs. In addition, the overall frequency of mutations in the incidental tumors (85%) did not differ significantly from that we previously reported in a series of 72 advanced/metastatic GISTs (86%), strongly supporting the view that activating mutations in KIT are acquired very early in the development of most GISTs. The findings suggest that KIT mutations per se are of little prognostic importance in GISTs.American Journal Of Pathology 06/2002; 160(5):1567-72. · 4.60 Impact Factor