1)悪性貧血

Pernicious Anemia

　悪性貧血は，胃底腺の壁細胞や内因子に対する抗体が血液中に見い出され，自己免疫的機序により惹起される病態である．通常，胃で内因子と結合し，回腸で吸収されるビタミンB₁₂の欠乏のためにDNA合成が障害された結果，巨赤芽球性貧血に陥る．X線的にも内視鏡的にも胃底腺領域での高度の粘膜萎縮を認め，生検でも固有の胃底腺はほとんど消失し，偽幽門腺もしくは腸上皮化性に置き換わっている所見を示し，胃液は無酸となる．一方，幽門腺粘膜は比較的よく保たれている．続発性疾患として，胃癌や多発胃カルチノイドの発生が知られている．

　Pernicious anemia would be caused by an autoimmune mechanism since parietal cell antibodies or/and intrinsic factor antibodies were discovered in the patient's serum. Synthesis of DNA was disturbed due to malabsorption of vitamin B12 combined with an intrinsic factor in the stomach, which led to magaloblastic anemia. X-ray and endoscopic examination showed the fundic mucosa of stomach to be atrophied, but the antral mucosa to be preserved. Histological examination of biopsy specimens obtained from the gastric body revealed the disappearance of the fundic glands and replacement with pseudopyloric glands or intestinal mucosa. Many reports have described a high incidence of gastric carcinoma or carcinoid tumors in patients with pernicious anemia.