5)皮膚筋炎

Dermatomyositis Complicated with Malignant Tumor

　皮膚筋炎と悪性腫瘍の合併率は30～40％である．皮膚筋炎症状と悪性腫瘍発現の時間的関係については60～80％の例で皮膚筋炎が先行するとされているがほぼ半年以内に両方とも発現している例が多い．悪性腫瘍のうち，胃癌との合併は本邦では高く，約40％を占める．しかし，胃癌の進行度は発見時既にStage III～IVの進行癌がほとんどで，早期癌での発見は少ない．占居部位は胃上部に多く，組織型の関係は認められなかった．悪性腫瘍の治療によりしばしば皮膚筋炎の症状が軽快するとの報告がみられ，皮膚筋炎の発症に悪性腫瘍が深く関与することを示唆している．臨床で皮膚筋炎を認めた場合，内臓悪性腫瘍，特に消化管癌の検索は極めて重要である．

　Dermatomyositis often complicates malignant tumor and it is reported to occur in 30～40％ of cases of malignant tumor. Most cases of dermatomyositis with malignant tumor initially reveal the symptoms of dermatomyositis, but both diseases are finally diagnosed within 6 months. In Japan, 40 ％ of malignant tumors are gastric carcinomas diagnosed when they are in Stage III-IV of TNM classification, but are rarely diagnosed in their early stage. Gastric cancer is usually located at the upper part of the gastric body and has no relation to the histological type. It is highly suspected that malignant tumor plays some part in the etiology of dermatomyositis because there are so many reports of improvement of dermatomyositis after tumor therapy for example gastrectomy. Because of this relationship, observation of the gastrointestinal tract is necessary when dermatomyositis is found.