Shishido Tsutomu, Hiroshima Yuki, Uematsu Nozomu, Kazumoto Hiroko, Kaiume Hiroko, Kirihara Takehiko, Takeda Wataru, Ueki Toshimitsu, Sumi Masahiko, Kobayashi Hikaru
Department of Hematology, Nagano Red Cross Hospital.
Rinsho Ketsueki. 2018;59(6):675-681. doi: 10.11406/rinketsu.59.675.
An 81-year-old woman presented to our hospital with anemia. Complete blood counts revealed macrocytic anemia; however, serum vitamin B12 and folate levels were normal. Bone marrow aspiration revealed multilineage dysplasia, and the patient was initially diagnosed with refractory cytopenia and multilineage dysplasia subtype of myelodysplastic syndrome. However, blood smear revealed hypersegmented neutrophils and bone marrow aspiration showed remarkable megaloblastic changes of erythroid cells. Based on these findings, the patient was administered 1,500 µg mecobalamin per day on a trial basis. Three weeks after initiating mecobalamin, macrocytic anemia improved. Her hemoglobin levels were also normalized along with immediate resolution of peripheral blood dysplasia. The final diagnosis was pernicious anemia (PA) based on anti-intrinsic factor positivity and the efficacy of mecobalamin. Use of automated analyzers may be associated with falsely normal or falsely elevated vitamin B12 levels in the presence of anti-intrinsic factor antibodies. Our case suggests that trial administration of mecobalamin may be an important step to correctly diagnose PA associated with falsely normal or falsely elevated vitamin B12 levels, particularly when typical morphological features of PA are present.
一名81岁女性因贫血前来我院就诊。全血细胞计数显示为大细胞性贫血；然而，血清维生素B12和叶酸水平正常。骨髓穿刺显示多系发育异常，患者最初被诊断为难治性血细胞减少症和骨髓增生异常综合征的多系发育异常亚型。然而，血涂片显示中性粒细胞核分叶过多，骨髓穿刺显示红细胞有明显的巨幼样改变。基于这些发现，对患者进行了每日1500μg甲钴胺的试验性给药。开始使用甲钴胺三周后，大细胞性贫血有所改善。她的血红蛋白水平也恢复正常，外周血发育异常立即得到缓解。根据抗内因子阳性及甲钴胺的疗效，最终诊断为恶性贫血（PA）。在存在抗内因子抗体的情况下，使用自动分析仪可能会导致维生素B12水平出现假正常或假升高。我们的病例表明，甲钴胺试验性给药可能是正确诊断与维生素B12水平假正常或假升高相关的PA的重要步骤，特别是当存在PA的典型形态学特征时。
