Morphological features following G-CSF treatment.

RhG-CSF is widely used in hematology and oncology for the amelioration of chemotherapy induced neutropenia, for the restoration of neutrophil production after bone marrow transplantation, and for other conditions such as myelodysplastic syndromes, aplastic anemia and severe chronic neutropenia. Moreover, RhG-CSF is able to bring about a lot of functional and phenotype modifications in the induced neutrophils, but little has been reported about the morphological modifications induced by this growth factor. In particular, toxic granules, hypogranularity, Dohle bodies, abnormal nuclear lobulation (hypersegmentation or hyposegmentation), pseudo-Pelger-Huet nuclei, corkscrew-shaped nuclei, circular nuclei and dyschronism between nuclear and cytoplasmic maturation have all been reported; however, it must be pointed out that these findings refer to high rhGCSF dosages (40-60 μg/kg/day) given for a long period (about three weeks) immediately after high dose chemotherapy. We report some hitherto undescribed images of neutrophil abnormalities detected in peripheral blood smears of patients undergoing rhG-CSF at standard dosage(5 μg/kg/day) for a short period (5 days), far from direct cytostatic drug effects; in fact, the growth factor was administered in the last week of a 14-day interval between two chemotherapy courses. Moreover, to avoid any activation due to the circulating growth factor, the blood smears were prepared 24 hrs after the last rhG-CSF dose. Under these conditions, about 30% of neutrophils displayed several peculiar aspects along with the presence of abundant toxic granules: some cells presented membrane blebs, others showed two-horned pseudopodia, some were hand mirror shaped and others were cigar-shaped (Figure 1). These features might be the morphologic expression of hyperactivation, in agreement with the previously reported capacity of the drug to induce neutrophil polarization (which is considered to be the initial reaction of chemotaxis). Alternatively, they might be the morphologic expression of structural defects MORPHOLOGICAL FEATURES FOLLOWING G-CSF TREATMENT