リンパ増殖性疾患を除く間葉系腫瘍に対する免疫組織化学染色

Immunohistochemical Staining of Gastrointestinal Mesenchymal Tumors other than Lymphoproliferative Disorders

要旨●消化管間葉系腫瘍全体のうち約80%をGIST（gastrointestinal stromal tumor）が占める．消化管間葉系腫瘍の診断では，最も頻度が高く，著効を示す分子標的薬の存在するGISTの診断を間違えないことが重要となる．GISTの鑑別疾患には，比較的頻度の高い平滑筋腫や神経鞘腫をはじめとして，頻度は低いがその他の多種多様な軟部腫瘍も含まれる．GISTの鑑別診断にはKITの免疫染色が必須であり，紡錘型と類上皮型のGISTにおけるKITの免疫染色像の特徴を十分理解したうえで，鑑別すべき疾患における代表的な免疫染色パターンも考慮して，正確な診断をする必要がある．

　GISTs（gastrointestinal stromal tumors）are the most common mesenchymal tumors of the gastrointestinal tract. As very effective drugs targeting specific molecular targets can be used for the treatment of GIST, it is very important to accurately diagnose the mesenchymal tumors of the gastrointestinal tract. Because various types of soft tissue tumors may arise in the gastrointestinal wall, a precise differential diagnosis between GISTs and the other types of tumors needs to be done. Although most GISTs strongly express KIT, some PDGFRA-mutant epithelioid GISTs might not show immunohistochemically detectable KIT expression. For accurate differential diagnosis of various gastrointestinal mesenchymal tumors, knowledge of specific immunohistochemical staining pattern for each tumor type is required.