Iron-laden macrophage in autoimmune disease.

A 14-year-old African American adolescent boy presented with a 20-lb weight loss, malaise, and arthralgia. Physical examination was unremarkable. CBC showed pancytopenia with a hemoglobin level of 7.9 g/dL, leukocytes 1.2 3 10/L, and platelets 137 3 10/L. Peripheral smear showed occasional dacrocytes and schistocytes. Other testing showed a creatinine level of 1.3 mg/dL, 11 proteinurea, erythrocyte sedimentation rate of 99, iron level of 48 mg/dL, transferrin level of 114 mg/dL, and ferritin level of 1200 ng/mL. The bone marrow was mildly hypocellular, with erythroid hypoplasia, left-shifted granulopoiesis, and no evidence of malignancy. A bone marrow core biopsy was stained with (panel A) hematoxylin and eosin or (panel B) Prussian blue, indicating iron-laden macrophages. Titers of several autoantibodies were elevated, and a renal biopsy revealed nephritis. The final diagnosis was mixed connective tissue disease.