Hereditary Cystinosis Detected by CD68 Staining of the Bone Marrow Biopsies of 2 Siblings.

Cystinosis is an autosomal recessive lysosomal storage disease. We present 2 siblings in whom cystinosis was detected by CD68 immunohistochemical analysis of bone marrow biopsies. The older patient was a 6-year-old boy who had been receiving erythrocyte suspension therapy for 5.5 years because of low hemoglobin levels. The patient was admitted to our hospital because of hepatomegaly, anemia, and thrombocytopenia and underwent a trephine bone marrow biopsy based on a preliminary diagnosis of lipid storage disease. Macrophage-like cells were observed in the hematoxylin/eosin-stained sections. These cells were stained for CD68 to confirm that they were macrophages. Some crystalline structures were seen in the cytoplasm of the macrophages after CD68 staining. These structures were thought to be cystine crystals. The diagnosis of cystinosis was confirmed by a clinical assessment. The 1-year-old sibling of the patient was also examined; this sibling exhibited renal disease and had a family history of consanguineous marriage. Cystinosis was also detected in this sibling by clinical assessment and staining of the patient's trephine bone marrow biopsy for CD68. The staining of the bone marrow biopsies for CD68 enabled the patient and his sibling to be diagnosed with cystinosis; these patients were not correctly diagnosed over the previous 6-year period. No similar report was found in the literature regarding this topic.