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Carcinoma is a type of cancer that develops from epithelial cells. Specifically, a carcinoma is a cancer that begins in a tissue that lines the inner or outer surfaces of the body, and that generally arises from cells originating in the endodermal or ectodermal germ layer during embryogenesis.〔(【引用サイトリンク】title=Definition of Carcinoma )〕 Carcinomas occur when the DNA of a cell is damaged or altered and the cell begins to grow uncontrollably and become malignant. It is from the Greek καρκίνωμα 'karkinoma' meaning sore, ulcer, or cancer, itself derived from ''karkinos'' 'crab'.〔''Oxford English Dictionary, 3rd edition, (''s.v.'' )〕 ==Classification== As of 2004, no simple and comprehensive method for classifying has been devised and accepted within the scientific community.〔 Traditionally, however, malignancies have generally been classified into various types using a combination of criteria, including:〔 the cell type from which they start, specifically: #Epithelial cells ⇨ carcinoma #Non-hematopoietic mesenchymal cells ⇨ sarcoma #Hematopoietic cells ##bone marrow-derived cells that normally mature in the bloodstream ⇨ Leukemia ##bone marrow-derived cells that normally mature in the lymphatic system ⇨ Lymphoma #Germ cells ⇨ Germinoma Other criteria that play a role in a cancer diagnosis include: *The degree to which the malignant cells resemble their normal, untransformed counterparts *the appearance of the local tissue and stromal architecture *the anatomical location from which tumors arise *genetic, epigenetic, and molecular features 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「carcinoma」の詳細全文を読む スポンサード リンク
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