We studied 5 patients with essential thrombocythemia utilizing glucose-6-phosphate dehydrogenase (G-6-PD) enzyme as a cell marker for determining clonality. One of the patients was found to be heterozygous for isoenzymes B and A in the nonhaemopoietic tissues such as fibroblasts, but manifested only isoenzyme type B in the erythrocytes, neutrophils, and platelets. Our studies support the concept that essential thrombocythemia is a clonal disorder arising in a multipotent stem cell.

We present a case of a 64-year-old male, diagnosed to have acute promyelocytic leukemia with trisomy 21. He came to the hospital with bleeding secondary to disseminated intravascular coagulation. Promyelocytes in the blood and bone marrow contained abundant, prominent azurophilic granules. Cytogenetic studies revealed trisomy 21. The karyotypic abnormality reverted back to normal 46,XY, pattern after chemotherapy. The typical morphologic and cytogenetic features of acute promyelocytic leukemia are briefly discussed.

An 86-year-old man, diagnosed as having carcinoma of the prostate, stage D, was admitted to the hospital. Soon after admission, he developed bleeding from various sites, including intravenous puncture sites and gastrointestinal and urinary tracts. A clinical diagnosis of disseminated intravascular coagulation (DIC) was made, which was corroborated by laboratory data. A factor VIII inhibitor of 12.5 Bethesda units was also identified in the patient's plasma. Concomitant occurrence of disseminated intravascular coagulation and an acquired factor VIII inhibitor has not been reported previously.