病理からみた分類困難な炎症性腸疾患

Clinicopathological Re-analysis of Enterocolitis Indeterminate (Unclassified)

要旨　外科切除例の初回病理診断で，分類困難腸炎は2％（非腫瘍性腸疾患852例中17例）であった．再検討で，その頻度は0.5％（4/852）となった．訂正診断例は，感染性腸炎（8例），虚血性回腸炎（1例），単純性腸潰瘍（1例），小腸結核（1例），潰瘍性大腸炎（1例），およびYersinia感染症（1例）であった．再検後も分類困難腸炎の4例は，粘膜内病変の完治例，回盲弁上の大腸炎（2例）と多発・発赤・広基の，隆起性病変であった．後二者ないし後一者が新しい型の腸炎と考えられた．初回の分類困難腸炎は，再検討で，そのほとんどが分類可能となった（今回は13/17例76％）．分類困難腸炎となる最大の原因は，①診断者の実力不足と，②検索方法・検索精度の不十分さ，とにある．このほかに，③病変の肉眼的特徴を残さない，既知疾患の完治，④既知疾患に合併した二次変化，もある．そして，真の新しい炎症性腸疾患は，今回の検討で，1～2種あると推定された．

　Enterocolitis indeterminate accounted for 2.0％ (17/852) of surgically resected small and large intestines at the first pathological examination. The proportion, however, decreased to 0.5％ (4/852) when reexamined clinicopathologically, i.e., 76％ (13/17) of the cases once classified into enterocolitis indeterminate were put into one of the known inflammatory bowel diseases.

　Revised diagnoses were as follows: bacterial infective (entero-) colitis (8 cases), ischemic colitis (1), simple ulcer (1), tuberculosis (1), ulcerative colitis (1) and Yersinial infection (1). The remaining unclassifiable colitis (4 cases) were described as follows: completely healed mucosal lesion (1 case), active colitis with a circular and three oval shallow ulcers on the ileocecal valve (2), and multiple sessile and round to oval caterpillar-like polyps with smooth red surface in the sigmoid colon and rectum (1). The last one or two pathological findings may lead to new categories of inflammatory bowel diseases.

　Seventy-six percent of misclassifications occurred at the first pathological examination because of pathologists' poor knowledge on inflammatory bowel diseases or methodologically inadequate and inaccurate examination. Misclassifications in the rest of the cases were due to the lack of pathognomonic findings of the known bowel diseases which had already healed completely or developed complications.