Immunophenotypic profile of myeloid cells in granulocytic: Sarcoma by immunohistochemistry - Correlation with blast differentiation in bone marrow

The present study was designed to evaluate the lineage differentiation (par ticularly monocytic differentiation) of immature myeloid cells in granulocy tic sarcoma (GS) by immunohistochemistry and correlate the results with lin eage differentiation of blasts in the bone marrow and to determine the degr ee of maturation of the infiltrating myeloid cells in GS by immunohistochem istry using CD34 and HLA-DR. Immunohistochemical stains were performed on p araffin-embedded tissue from 17 GS lesions with lineage-associated markers: myeloperoxidase, CD68 (KP1), CD68 (PG-Ml), glycophorin A, factor VIII, and CD56; and with markers for blasts and immature myeloid cells: CD34 and HLA -DR. Our results show that positive staining with PG-MI, but not KPI, sugge sts monocytic differentiation of myeloid cells in GS and correlates with th e monocytic differentiation of blasts in the bone marrow Expression of CD56 is frequent in GS, especially when the marrow blasts have monocytic differ entiation and should not be interpreted as a primary natural-killer cell pr ocess. The immature myeloid cells in CS are frequently HLA-DR positive. How ever, CD34 positivity of the immature myeloid cells is relatively uncommon, except in cases with underlying myelodysplastic syndrome or chronic myelog enous leukemia.