To the Editor.
—In discussing their case report, Hricik and Hussain1 remark, "Our patient's hepatosplenomegaly may have reflected compensatory extramedullary hematopoiesis associated with extensive bone marrow replacement by calcium oxalate crystals." Actually, the cause of the patient's organomegaly is obscure. The term compensatory hematopoiesis describes the reactive state of normal hematopoietic tissue. Evidence indicates that the patient's hematopoiesis was not normal. The leukoerythroblastic blood film and "teardrop" red blood cells (RBCs) are characteristic of the intravascular hematopoiesis that is found in chronic myeloproliferative diseases. Normal human hematopoiesis must be extra-vascular, and normal hematopoiesis requires the specialized microcirculation of the marrow.2 The suspicion of extramedullary hematopoiesis is somewhat offset by a ferrokinetic study demonstrating "No noteworthy change in the uptake of ferric chloride Fe 59... over the liver and spleen."1 This is evidence against erythropoiesis in those organs. Uptake of 59Fe by the marrow is not given