病理学的に胃癌と鑑別する必要がある炎症性病変

The Histological Appearances of Some Gastric Inflammatory Lesions that could be Mistaken for Malignancy

要旨　胃の良性の炎症性疾患のうち，組織学的に癌と類似した像を呈するため誤診する危険性があるものがある．日常の病理組織診断においては胃炎・消化性潰瘍に伴う幼弱な再生上皮や腸上皮化生で異型を呈するものが頻度は高いが，まれなものでは，①偽肉腫様細胞の出現，②ウイルス感染（サイトメガロウイルス），③EMR後の変性腺管，④部分的脾動脈塞栓術後の虚血性変化，⑤抗癌剤性胃炎，⑥Helicobacter胃炎（あるいはMALTリンパ腫）における印環細胞癌様細胞などがある．誤診を防ぐためには，このような病変で出現する異型細胞の特徴とその鑑別点を熟知しておく必要があるが，臨床診断と病理診断の乖離がある場合はお互いに討論することが最も重要なことであると思われる．

　Some inflammatory lesions of the stomach may be misdiagnosed as malignant tumors because of the presence of various atypical cells. The entities chosen for demonstration and discussion here are as follows. 1) Regenerative epithelium due to erosive gastritis or a peptic ulcer. 2) Pseudomalignant (pseudosarcomatous) cells in granulation tissue. 3) Viral infection. 4) Degenerative glands due to endoscopic mucosal resection. 5) Ischemic change due to partial splenic embolization. 6} Gastritis due to anti-cancer drugs. 7) Carcinoma-like signet ring cells in gastritis associated with Helicobacter pylori infection. The characteristic histological features are described and illustrated in this review. In order to prevent the misdiagnosis, pathologists must be familiar with the characteristic histological features of the atypical cells that appear in the above lesions. However, for the accurate diagnosis of each lesion, clinical information needs to be taken into consideration, so it is important that the clinician discuss the diagnosis with the pathologist when a pathological diagnosis differs from the clinical one.