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这名1岁女婴的病史包括生长发育异常、中度贫血、低磷酸盐血症、维生素D缺乏症、糖尿和蛋白尿。患儿接受诊断性骨髓穿刺，发现巨噬细胞比例增加至20%（正常为2~5%），其中可见多边形晶体。据此诊断为胱氨酸贮积症。该病为一种罕见的常染色体隐性遗传病，由于溶酶体膜表面蛋白——胱氨酸转运蛋白出现突变，导致溶酶体无法储存胱氨酸。游离的胱氨酸可在肾脏、肝脏、眼和大脑等器官的细胞溶酶体中积聚。诊断依据为观察到胱氨酸结晶，或白细胞的胱氨酸含量过高。若裂隙灯检查角膜或骨髓中可见胱氨酸结晶，亦可以作出诊断，但1岁以下患者常缺乏这些表现。患儿接受了半胱胺治疗，临床症状得到改善；但确诊8个月后因住院期间出现感染死亡。 参考文献 Vicari, P. and V.M. Sthel, Cystine Crystals in Bone Marrow. New England Journal of Medicine, 2015. 373(23): p. e27. A 1-year-old girl presented with a history of growth failure, mild anemia, hypophosphatemia, hypovitaminosis D, glucosuria, and proteinuria. She underwent diagnostic bone marrow aspiration, which revealed an increased proportion of macrophages containing polygonal crystals (20%; normal range, 2 to 5%), which are pathognomonic for cystinosis. A rare autosomal recessive disorder, cystinosis is caused by a defect in lysosomal storage of the amino acid cysteine, typically owing to a mutation in cystinosin, a lysosomal membrane protein. Free cystine accumulates in lysosomes in cells, including cells in the kidneys, liver, eyes, and brain. The diagnosis is made by observing cystine crystals or by measuring the cystine content of leukocytes. Although cystine crystals that are observed in the cornea on slit-lamp examination or in the bone marrow are diagnostic of cystinosis, they may be absent in patients younger than 1 year of age. The child began cysteamine treatment and had improvement in clinical symptoms; however, 8 months after the diagnosis of cystinosis, the child died from a generalized infection during a hospital admission. |
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