腸管感染症の生検病理診断

Pathological Diagnosis of Intestinal Tract Infection in Biopsy

要旨●腸管感染症には，組織学的に非特異的な炎症所見を呈し病原微生物の推定が困難な疾患と，組織学的に特徴的所見を呈し病原性微生物の同定や推定が可能な疾患が存在する．細菌性腸管感染症の大多数は非特異的な炎症所見を呈する．微生物学的検査で原因細菌が同定された細菌性腸管感染症34症例の生検組織像の病理学的特徴として，①腺管のねじれ（8.8％），腺萎縮（0.0％），Paneth細胞化生（8.8％）はほとんど認められない，②炎症細胞の分布は巣状（85.3％），表層性（52.9％）と不均一な分布を示すことが多い，③炎症細胞浸潤は好中球浸潤が目立つ例が大多数を占め（97.1％），好中球浸潤数のリンパ球・形質細胞浸潤数に対する比率が0.5以上の症例がほとんどである（85.3％），④陰窩炎（67.6％），陰窩膿瘍（44.1％）が高頻度にみられ，陰窩膿瘍は全例が腺管管腔の拡張を伴わない非拡張型の陰窩膿瘍である，が挙げられる．細菌性腸管感染症と初発時の潰瘍性大腸炎の生検組織所見の比較では，単変量解析にて有意な相関を示し，多変量解析で独立性の認められた生検組織所見は，細菌性腸管感染症を示す所見では“表層性の炎症細胞分布”，“好中球/リンパ球・形質細胞≧0.5”，初発時の潰瘍性大腸炎を示す所見では“basal plasmacytosis”であった．これらに加え，組織学的に病原微生物の同定や推定が可能な代表的な腸管感染症を列挙し，その組織像について概説した．

　Intestinal tract infections include diseases that present histologically nonspecific inflammation caused by pathogenic microorganisms that are difficult to estimate and diseases with histologically characteristic findings caused by pathogenic microorganisms that can be identified and estimated. The majority of bacterial enteric infections exhibit nonspecific inflammation. The pathological features of biopsy tissue images of 34 cases of bacterial enteric infections with causative bacteria identified by microbiological examination are as follows：（1）Hardly any gland twisting（8.8%）, gland atrophy（0.0%）, or Paneth cell metaplasia（8.8%） ; （2）Commonly exhibit focal distribution of inflamed cells（85.3%）and superficial non-uniform distribution of inflamed cells（52.9%） ; （3）Many demonstrate prominent neutrophil infiltration in inflamed cell infiltration（97.1%）, with most（85.3%）having a neutrophil infiltration to lymphocyte/plasma cell invasion ratio of 0.5 or higher ; （4）High occurrence of cryptitis（67.6%）or crypt abscess（44.1%）. All cases of crypt abscess were non-expanded and not accompanied by expansion of ductal lumen.

　In the comparison of biopsy tissue findings of bacterial intestinal infection and initial ulcerative colitis, univariate analysis showed significant correlations, with biopsy tissue showing independence in multivariate analysis. Findings revealed that bacterial enteric infections had “superficial inflammatory cell distribution” and “neutrophil/lymphocyte/plasma cells of ≧0.5” and that ulcerative colitis had “basal plasmacytosis”.

　In addition, for histological identification and estimation of pathogenetic microorganisms, typical examples of intestinal tract infections were given and an overview of the histology was provided.