未分化型混在早期胃癌の臨床病理学的特徴とリンパ節転移

Clinicopathological Characteristics of Differentiated Mixed-type Early Gastric Carcinoma with Lymph Node Metastasis

要旨　自験外科切除早期胃癌756例（M癌614例，SM1癌142例）を用い，未分化型混在分化型胃癌の臨床病理学的特徴と転移を中心に検討を行った．756例のうち分化型混合型癌（以下混合型癌）は9.7％（73/756例）で，その85％（62/73例）が胃型粘液形質を有し，分化型純粋型癌（以下純粋型癌）や未分化型癌と比較しSM1癌（34.2％），リンパ管侵襲陽性（9.6％）の頻度が高く，腫瘍最大径の平均が大きい（39.0mm）傾向にあった．また混合型癌の転移率はM癌6.3％（3/48例），SM1癌12.0％（3/25例）といずれも未分化型癌と同様に高率で，そのrisk factorとして随伴潰瘍（6/6例）（p＜0.05），大きい病変（平均67.2mm）（p＜0.01），リンパ管侵襲（2/6例）（p＜0.05）が挙げられた．しかし病変内における未分化型癌の占める割合と転移との間に相関はみられず，また腫瘍粘膜下層先進部のsm INFγ所見（sprouting陽性もしくは先進部組織型が未分化型）は混合型SM1癌に多くみられ，リンパ管侵襲を高頻度に認めるが，リンパ節転移のrisk factorとは言えなかった．分化型癌484例（M癌387例，SM1癌97例）における深達度，組織型，随伴潰瘍，大きさ，リンパ管侵襲とリンパ節転移の検討では，大きさが20mm以下なら深達度，組織型，潰瘍の有無にかかわらず転移はなかったが，潰瘍を合併した混合型M癌は30mmから，SM1癌では23mmから転移がみられ，特に潰瘍およびリンパ管侵襲を伴う混合型SM1癌の転移率は50％（2/4例）と高率であった．以上より混合型M，SM1癌の治療は未分化型癌と同様の取り扱いも考慮する必要があると考える．

　We studied surgical specimens from 756 cases of early gastric carcinomas (M, SM1) that were histopathologically examined at the Department of Pathology, Chikushi Hospital, Fukuoka University, Japan, between January 1990 and March 2007, and, clinicopathologically, we evaluated characteristics of differentiated mixed-type carcinoma with lymph node metastasis.

　The incidence of differentiated mixed-type carcinoma was 9.7％ (73 cases) among 756 cases of early gastric carcinomas. The differentiated mixed-type carcinoma tends to be larger than, the differentiared pure-type and undifferentiated type carcinoma and it also has ulceration and lymphatic permeation more frequently than the latter. The mucin phenotype of almost all differentiated mixed-type carcinomas are, immunohistochemically, gastric mucin phenotype (46.6％) or gastric and intestinal mucin phenotype (38.4％). The incidence of lymph node metastasis of intramucosal (M) differentiated mixed-type carcinoma was 6.3％ (3/48 cases), and submucosal(SM1) differentiated mixed-type carcinoma was 12.0％ (3/25 cases). The differentiated mixed-type carcinomas with lymph node metastasis were characterized by:large size (p＜0.01), presence of ulceration (p＜0.05), and with lymphatic permeation (p＜0.05). We investigated 97 cases of differentiated-type submcosal carcinoma, and the lesions which were differentiated mixed-type carcinoma and/or were larger than 21mm in size sometimes show sm INFγsuch as poor differentiation (p＜0.01) and/or sprouting (p＜0.05) in the submucosal invasive front of the tumor, and differentiated mixed-type carcinomas with sm INFγtend to have lymphatic permeation (p＜0.05). We examined the relationship between clincopathological features of 484 cases of differentiated-type early gastric carcinomas (M, SM1), taking account especially of depth, histological type, presence of ulceration, lymphatic permeation, and size. All early gastric carcinomas (M, SM1) without lymph node metastasis were in depth and histological type with or without ulceration smaller than 20mm in size, and the incidence of lymph node metastasis of SM 1 differentiated mixed-type carcionomas with ulceration and lymphatic permeation was 50％ (2/4 cases).