消化管粘膜下腫瘍の病理，組織分類（GISTの概念を含めて）

Pathology and Classification of Gastrointestinal Submucosal Tumors Including GIST

要旨　gastrointestinal stromal tumor（GIST）は消化管の粘膜下腫瘍，特に臨床的に問題となる非上皮性腫瘍で最も頻度が高い組織型である．このGISTにおいてc-kit遺伝子の突然変異が組織発生に大きく関係し，その遺伝子産物であるKITが発現することが見い出されたことから，免疫組織化学的にKIT陽性の間葉系紡錘形ないしは上皮様細胞腫瘍をGISTと定義するのが妥当である．GISTにおいては多彩な組織像やKIT染色パターンがみられ，GIST以外の軟部腫瘍で時に意外なKIT陽性所見が認められる．GISTの病理診断のためには，形態学的所見と照らし合わせながら，KITに加えて汎用性の高いCD34，デスミン，平滑筋アクチン，S-100，ケラチンに対する抗体を用いた免疫染色パネルによって他の紡錘形細胞腫瘍を鑑別することが必要である．

　Gastrointestinal stromal tumors (GIST) are clinically the most common non-epithelial neoplasms among submucosal tumors of the gastrointestinal (GI) tract. Based on the facts that there are activating c-kit mutations and KIT expression in many GIST, it is reasonable to define GIST as KIT-positive mesenchymal spindle or epithelioid cell lesions. There have been a variety of histologic and KIT staining patterns in GIST, and occasionally there has been unexpected KIT positivity in soft tissue tumors other than GIST. For diagnosis of GIST, it is necessary, in light of the morphologic findings, to differentiate other spindle cell tumors of the GI by immunohistochemistry, using widely used antibodies for CD34, desmin, smooth muscle actin, S-100and cytokeratin as well as KIT.

　1) Division of Pathology, National Cancer Center Research Institute and Hospital, Tokyo

　2) Division of Clinical Laboratory, National Cancer Center Research Institute and Hospital, Tokyo