Color Atlas of Hematology - Practical Microscopic and Clinical ...

122Abnormalities of the White Cell SeriesOsteomyelosclerosisWhen anemia accompanied by moderately elevated (although sometimesreduced) leukocyte counts, thrombocytopenia or thrombocytosis, clinicallyevident splenic tumor, left shift up to and including sporadic myeloblasts,and eosinophilia, the presence of a large proportion of red cell precursors(normoblasts) in the differential blood analysis, osteomyelosclerosisshould be suspected. BCR-ABL gene analysis is negative.Pathologically, osteomyelosclerosis usually originates from megakaryocyticneoplasia in the bone marrow and the embryonic hematopoieticorgans, particularly spleen and liver, accompanied by fibrosis(= sclerosis) that will eventually predominate in the surrounding tissue.The central role of cells of the megakaryocyte series is seen in the giantthrombocytes, or even small coarsely structured megakaryocyte nucleiwithout cytoplasm, that migrate into the blood stream and appear in theCBC. OMS can be a primary or secondary disease. It may arise during thecourse of other myeloproliferative diseases (often polycythemia vera oridiopathic thrombocythemia).Tough, fibrous material hampers the sampling of bone marrow material,which rarely yields individual cells. This in itself contributes to thebone marrow analysis, allowing differential diagnosis versus reactive fibroses(parainfectious, paraneoplastic).Characteristics of OMSAge of onset: Usually older than 50 years.Clinical findings: Signs of anemia, sometimes skin irritation, drasticallyenlarged spleen.CBC: Usually tricytopenia, normoblasts, and left shift.Further diagnostic procedures: Fibrous bone marrow (bone marrowhistology), when appropriate and BCR-ABL (always negative).Differential diagnosis: Splenomegaly in cases of lymphadenoma orother myeloproliferative diseases: bone marrow analysis.Myelofibrosis in patients with metastatic tumors or inflammation:absence of splenomegaly.Course, therapy: Chronic disease progression; transformation is rare.If there is splenic pressure: possibly chemotherapy, substitution therapy.Further myeloproliferative diseases are described together with the relevantcell systems: polycythemia vera (see p. 162) and essential thrombocythemia(see p. 170).