潰瘍性大腸炎の治療経過中にIBDUと診断された1例

Ulcerative Colitis that Transitioned to Inflammatory Bowel Disease Unclassified, Report of a Case

要旨●分類不能腸炎（IBDU）症例の中では当初は潰瘍性大腸炎またはCrohn病と診断されるものの，治療経過中にもう一方の疾患の特徴を併発し，IBDUと判断される症例がある．筆者らは若年で潰瘍性大腸炎を発症し，経過中に肛門病変の合併がみられ，次第に大腸型Crohn病として特徴的な所見を呈した症例を経験した．IBDUと診断したことで，寛解導入療法として抗TNFα抗体製剤の倍量投与を行うことができた．適切な診断は薬剤選択を含めた治療方針決定に関わるため，治療経過中であっても画像所見の変化に注意することが重要と考える．

　In certain cases of IBD（inflammatory bowel disease）, after an initial diagnosis of ulcerative colitis or Crohn's disease is made, the patient may exhibit features of the other disease and, thus, may be re-classified as having IBDU（IBD unclassified）. Herein, we encountered a case of a patient with young-onset ulcerative colitis who developed perianal lesions during treatment and subsequently exhibited the hallmarks of colonic-type Crohn's disease. The diagnosis of IBDU led to remission by intensifying the dose of anti-TNFα antibody therapy. Changes in imaging findings should be carefully monitored even during treatment, as an accurate diagnosis is crucial in determining the treatment strategy.