TRANSIENT INCREASE IN BLASTS MIMICKING ACUTE-LEUKEMIA AND PROGRESSINGMYELODYSPLASIA IN PATIENTS RECEIVING GROWTH-FACTOR

Previous studies of the hematologic effects of granulocyte colony-stim ulating factor (G-CSF) and granulocyte-macrophage colony-stimulating f actor (GM-CSF) have emphasized the morphologic changes induced by thes e growth factors, but few have reported increases in blasts. Here, we report six cases in which growth factor treatment resulted in a marked but temporary increase in peripheral and bone marrow blasts that led to diagnostic confusion with acute leukemia and high-grade myelodyspla stic syndromes. Five of the six patients were receiving treatment for hematologic malignant neoplasms, and one patient had an optic nerve ge rminoma. Growth factor treatment included single agent therapy with G- CSF (three patients), GM-CSF (one patient), or simultaneous therapy wi th G-CSF and GM-CSF (two patients). In two patients, there was a drama tic increase in blasts in the peripheral blood (39% and 20%), whereas four had substantial increases in blasts on the aspirate smear (8%-41% ). One patient had a medium-sized blast cluster shown on the core biop sy specimen. The blasts decreased after removal of growth factor in al l patients. The findings indicate that growth factor therapy can cause a substantial transient increase in blasts in the bone marrow and per ipheral blood that may be confused with relapse of acute leukemia or p rogression of a myelodysplastic syndrome.