Ultrastructure of megakaryocytes in the human bone marrow of patients with primary (essential) thrombocythemia.

An ultrastructural study was performed on bone marrow specimens in 10 patients (5 males/5 females, median age 53 years) with primary (essential) thrombocythemia (PTH) and an excessive elevation of the platelet count (1,625 +/- 783 x 10(9)/l). In contrast to a not severely altered neutrophilic granulo- and erythrocytopoiesis, megakaryocytes showed conspicuous large to giant forms. These were characterized by a highly lobulated nucleus containing several nucleoli and an extensive intermediate zone of the cytoplasm with many Golgi fields, numerous profiles of the so-called demarcation membrane system and an abundance of alpha-granules and some dense bodies.

Chronic myeloproliferative diseases with an elevated platelet count (in excess of 1,000,000/microliter): a clinicopathological study on 46 patients with special emphasis on primary (essential) thrombocythemia.

A clinicopathological study was performed on 46 patients with chronic myeloproliferative diseases (CMPD) showing a thrombocythemia in excess of 1,000 x 10(9)/liter. When applying rigid diagnostic criteria only 23 patients were compatible with the initially suspected diagnosis of primary thrombocythemia (PTH). Comparison of PTH with the other entities of CMPD (CGL, 10, AMM, 6, and polycythemia, 7 cases) revealed a sustained elevation of the platelet count observable over a period of 2 to 8 years, no marked leukocytosis or abnormalities of the differential blood count, and a normal score of the leukocyte alkaline phosphatase.