[1509] Megakaryocytic Hyperplasia Associated with Granulocyte-Colony Stimulating Factor

Lauren N Parsons, Horatiu Olteanu, Steven H Kroft, Alexandra M Harrington. Medical College of Wisconsin, Milwaukee, WI

Background: Granulocyte colony stimulating factor (G-CSF) is used to bolster bone marrow (BM) recovery following chemotherapy or stem cell transplantation. G-CSF promotes proliferation and maturation of neutrophils via interaction with receptors on neutrophils and granulocytic precursors; these receptors are virtually absent on precursor cells of the erythroid and megakaryocytic lineage. Anecdotally, we have observed megakaryocyte hyperplasia, in addition to the expected myeloid expansion, in the BMs of patients (pts) with recent G-CSF administration and therefore sought to systematically study this phenomenon.
Design: BMs from pts receiving G-CSF within 2 weeks of BM biopsy were compared to control BMs from pts in whom there was no G-CSF administration. Megakaryocytes were enumerated in each case by examining five 20x fields of an H&E-stained core biopsy. Megakaryocyte morphology was examined on the core biopsy and the Wright-Giemsa-stained aspirate smear. Atypical morphology was defined as frequent enlarged, hyperconvoluted and/or small, hypolobate forms. Clusters were defined as loose collections of >1 megakaryocytes. BM cellularity, myeloid/erythroid ratio (M/E), and peripheral blood counts were recorded.
Results: 38 pts who received G-CSF (19 males, 19 females, ages 21-76 years) and 18 control pts (14 males, 4 females, ages 26-84 years) were identified. The median white blood cell and platelet counts for the G-CSF patients were 12.3k/μL (1.6-34) and 153k/μL (175-491) respectively vs 5.4k/μL (4.3-15.4; p=0.04) and 171k/μL (157-536; p=0.592) in the controls, respectively. Median BM cellularity was 75% in the G-CSF pts and 48% in the control pts (p<0.001); average M/E were 6.1 and 2.7 in the study and control pts, respectively. Megakaryocytes per five 20x fields averaged 39.8 (range 3-114) in the G-CSF group, compared to 23.3 in controls (range 2-59, p=0.023). Megakaryocytes were clustered in 26/38 (68%) G-CSF cases, as compared with 11/18 (61%) control cases (p=0.77). Megakaryocyte morphology was atypical in 8/38 (21%) cases of G-CSF pts vs 1/18 (5.6%) control pts (p=0.245).
Conclusions: BMs from pts on G-CSF have nearly twice the mean number of megakaryocytes as control BMs. However, platelet counts were not significantly different between the two groups, despite the difference in megakaryocyte numbers. Megakaryocyte clustering and atypia was not significantly different between the two groups. To the best of our knowledge, this is the first documentation of megakaryocyte hyperplasia in association with G-CSF administration.
Category: Hematopathology

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 247, Wednesday Afternoon


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