口腔・咽喉頭の組織学と表在型咽頭癌の病理学的特徴

Histology of the oral cavity, laryngopharynx and pathological characteristics of superficial pharyngeal carcinoma

要旨

食道に至るまでの消化管の入り口は，口腔，上咽頭，中咽頭，下咽頭であり，咽頭に隣接して喉頭が存在する。口腔・咽頭の表面は重層扁平上皮に覆われるが，上咽頭，中咽頭では上皮下にリンパ組織（扁桃組織）を伴う部分がある。咽頭に発生する癌はほとんどが扁平上皮癌であるが，上咽頭ではEpstein-Barr virusが関係し著明なリンパ球浸潤を伴うlymphoepithelial carcinomaが，中咽頭ではHuman papilloma virus陽性の癌が特徴的である。下咽頭扁平上皮癌の内視鏡所見（通常，拡大とも）は食道のそれと類似する。咽頭領域には，食道と異なり粘膜筋板が存在しないため，上皮下結合織は粘膜下層とせずに上皮下層と呼称し，壁深達度としてtumor thicknessを評価する。

　The entrances of the digestive tract leading to the esophagus are the oral cavity, nasopharynx, oropharynx, and hypopharynx, and the larynx is adjacent to the pharynx. The surfaces of the oral cavity and pharynx are covered with stratified squamous epithelium, and the nasopharynx and oropharynx have areas with lymphoid (tonsillar) tissue beneath the epithelium. Most cancers occurring in the pharynx are squamous cell carcinomas. Lymphoepithelial carcinomas associated with Epstein-Barr virus and human papilloma virus-positive cancers are characteristic in the nasopharynx and in the oropharynx respectively. Endoscopic findings (both conventional and image-enhanced magnified) of hypopharyngeal squamous cell carcinoma are similar to those of the esophagus. Unlike the esophagus, the pharyngeal region does not have muscularis mucosae, so the subepithelial connective tissue is called the subepithelial layer instead of the submucosal layer. Tumor thickness should be evaluated as representing the depth of invasion.