Some speculations on the myeloproliferative syndromes.

Some Speculations on the Myeloproliferative Syndromes W ITH ACCUMULATING EXI ERIENCE, it becomes more and more evident that the bone marrow cells-enythrobhasts, granulocytes, megakar-vocvtes-often proliferate en masse or as a unit i-ather than as single elements. Thus, heukocytosis an(h thIOml)OcytOsis, as well as reticuhocytosis occur not only in 1)enign reversible cond!itions such as hemorrhage and excessive hemolysis 1)tlt in such malignant ormore or less irreversible reactions as leukemia and! pohycythemia. Although we seem to have become conditionet! to the idea that such entities as chronic gianulocytic leukemia and pohycythemia vera represent “pule” prohifemations of one or another cell type, a revision in this thinking max’ be necessary. Foi example, in most early cases of chronic granuiocytic leukemia, there is some dhegIee of eiythmocytosis and thrombocytosis. The latter may be of extraoidinary degree and attended with the presence of bits of megakai-yocvtes in the cim-culation. Thrombocvtosis often persists until the very end! of the d!isease and at times may dominate the picture. Simiharly, pohycythemia vera is far more than a pure red cell proliferation. The 1)100(1 picture ieveahs pancytosis’ (erythi-ocytosis, leukocytosis, thrombocytosis) an(l the marrow shows generalized hypercelluharity often dominated! by extieme increases in the megakaryocytes. Some cases of othetwise clear-cut 1)ol ’(themia have leukocvte counts in the neighborhoodl of 50,000 to 100,06’O with fain miumbers of myelocytes in the 1)100(1. How should one t-lassify these cases? Aie they atypical granulocytic leukemia with erythrocytosis resembhing polycytisensia vema or are they examples of polycythemia vera with a heukemoidl ieactiofl. Ims some cases of polycythemia slRwving relatively slight emythmocytosis, the platelet count may reach levels of five to ten million