Blackwell Publishing Journal Backfiles 1879-2005
Aims : To study the immunohistochemical and histological features of 158 gastrointestinal stromal tumours (GISTs), consisting of 137 tumours with mutations in c-kit and platelet-derived growth factor receptor-alpha (PDGFRα) genes and 21 wt-GISTs. Additionally, we evaluated the localization of PDGFRα in the normal intestine. PDGFRα gene mutations were recently described in a subset of GISTs and it has been hypothesized that PDGFRα-mutated tumours represent a distinctive entity among GISTs.Results : PDGFRα was expressed in ganglion bodies of the myenteric plexus and in Schwann cells but not in interstitial cells of Cajal. In contrast to other GISTs, tumours with PDGFRα mutations had an epithelioid phenotype and multinuclear giant cells. Kit was down-regulated in PDGFRα-mutated GISTs and PDGFRα expression was decreased in c-kit mutated tumours. Dot-like staining of Kit and PDGFRα was associated very frequently with mutation within the respective gene.Conclusions : Features of PDGFRα-mutated GISTs are multinuclear giant cells and dot-like staining for PDGFRα. In contrast, c-kit-mutated GISTs display a spindle cell phenotype and Kit-dots on immunohistochemistry. Our findings not only help to distinguish distinctive entities of GISTs using histological and immunhistochemical features, but also indicate that Kit and PDGFRα are differentially regulated in a subset of GISTs.
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