Walsh & Hoyt: Diagnosis

The diagnosis of agnogenic myeloid metaplasia is based on symptoms and signs and is established by blood smear and bone marrow biopsy. Marked anemia is found in 50% of patients. The blood smear is characteristically leukoerythroblastic, reflecting bone marrow fibrosis, and the red cells show marked anisocytosis and poikilocytosis. Teardrop-shaped erythrocytes reflect splenic extramedullary erythropoiesis. Nucleated red blood cells are common. In 50% of patients, the white blood cell count is elevated and may show all types of granulocytes. Bone marrow biopsy shows various degrees of fibrosis, increased megakaryocytes, distended sinusoids with intravascular hematopoiesis, and osteosclerosis. Bone marrow aspirate is nondiagnostic.