大腸腺腫扁平上皮化生の免疫組織学的研究 Immunohistochemical Analysis of Squamous Metaplasia of Colorectal Adenoma

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原著目的:免疫染色を用いて大腸腺腫における扁平上皮化生の網羅的検索を行い,その臨床病理学的・組織学的特徴,生物学的特性を明らかにする.対象および方法:大腸腺腫1238 例を対象に,サイトケラチン5(cytokeratin-5:CK5)免疫染色で扁平上皮細胞への分化を示す腺腫細胞を同定し,hematoxylin and eosin(HE)染色標本でその組織学的特徴を,involucrin 免疫染色で角化傾向の有無を,Ki-67 免疫染色で細胞増殖活性を,p53 免疫染色でp53 蛋白過剰発現の有無を解析した.結果:大腸腺腫の18.7% でCK5 陽性細胞が認められた.CK5 陽性細胞腺腫は,10 mm 以上の大きさ,絨毛または管状絨毛の組織型,高異型度併存,隆起型,有茎性が有意に多かった.CK5 陽性細胞は4 つの型に分類された.それらの中で,CK5 陽性細胞が充実胞巣を形成するType 2,3,4 が,組織学的所見からも扁平上皮化生巣と考えられたが,出現頻度はそれぞれ1.3,0.7,3.3% であった.Involucrin 陽性率は,Type3,2,4 の順に高かった.Ki-67 陽性率は,Type 2 がType 3,4 に比べ有意に高かったが,いずれの型も周囲腺腫部分に比べ有意に低値であった.p53 蛋白過剰発現を示した病巣はなかった.結論:大腸腺腫の扁平上皮化生は従来考えられていたよりも高頻度に生じる現象で,扁平上皮化生は腺腫の大きさの増大に伴って生じる外的刺激により起きると考えられた.扁平上皮化生には角化傾向の強いもの(角化型)と弱いもの(非角化型)の2 つのタイプが存在するが,いずれも細胞増殖活性は低く,p53 蛋白過剰発現もないことから癌化ポテンシャルはきわめて低い病変と考えられた.Background: We used immunohistochemical techniques to investigate the clinicopathologic, histologic, and biological characteristics of squamous metaplasia of colorectal adenoma. Methods: The study comprised 1238 colorectal adenomas. Immunostaining for cytokeratin-5 (CK5), involucrin, Ki-67, and p53 was used to detect adenoma cells with squamous differentiation, tendency toward keratinization, cell proliferation activity, and protein overexpression, respectively. Results: CK5 (+) cells were observed in 18.7% of samples and were significantly more frequent in adenomas larger than 10 mm and those with villous or tubulovillous histology, high-grade atypia, and a protruded or pedunculated gross configuration. CK5 (+) cells were classified into 4 types, and types 2, 3, and 4 were characterized by formation of solid nests and were defined as squamous metaplasia. The respective incidences were 1.3%, 0.7%, and 3.3%. The involucrin index was highest in type 3 and lowest in type 4. All type 2 and type 4 lesions had a significantly lower Ki-67 index than did their surrounding adenomatous areas and showed no p53 protein overexpression. Conclusions: Squamous metaplasia in colorectal adenoma was more frequent than was expected. Squamous metaplasia is believed to result from differentiation of glandular cells due to secondary stimulation in accordance with adenoma growth. It can be divided into keratinizing and nonkeratinizing types. Because of its low proliferation and lack of p53 protein overexpression, squamous metaplasia has an extremely low malignant potential.

収録刊行物

  • 東邦医学会雑誌

    東邦医学会雑誌 59(2), 60-67, 2012-03

    東邦大学医学会

各種コード

  • NII論文ID(NAID)
    120005306355
  • NII書誌ID(NCID)
    AN0016685X
  • 本文言語コード
    JPN
  • 資料種別
    Journal Article
  • 雑誌種別
    大学紀要
  • ISSN
    0040-8670
  • NDL 記事登録ID
    023535661
  • NDL 請求記号
    Z19-388
  • データ提供元
    NDL  IR 
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