Bone marrow core biopsy showing large cluster of blasts with admixed hemopoietic elements (H&E, 40x).
High power view of aggregate of primitive-appearing blasts in core biopsy (Giemsa, 100x).
Area of relatively preserved hemopoiesis in core biopsy with hemophagocytic cell (arrow, H&E, 40x).
CD34 immunohistochemical stain of core biopsy highlighting blasts (20x).
CD3 staining of subset of blasts. Weak staining of some of the larger cells is consistent with cytoplasmic staining (40x).
CD117 staining of subset of blasts (40x).
Pax5 staining of subset of blasts (40x).
TdT staining of subset of blasts (40x).
Blasts are negative for MPO by immunohistochemistry (40x).
Bone marrow aspirate smear showing morphology of blasts in comparison to mature lymphocytes (Wright-Giemsa, 100x).
Bone marrow aspirate smear showing hemophagocytic cells (Wright-Giemsa, 100x).
Bone marrow aspirate smear showing mild nuclear-cytoplasmic asynchrony of maturing erythroid precursors (arrow, Wright-Giemsa, 100x).
8-color flow cytometry showing two distinct CD45dim+ blast populations. One population (gold) expresses CD19, CD10, TdT, CD34 (dim), and CD38. The second population (green) expresses CD34 (bright) and CD38, and is negative for CD19, CD10 and TdT.
Additional analysis for B-cell antigens shows that the B-lymphoid population (gold) expresses very dim CD20 and is negative for surface kappa and lambda immunoglobulin light chains. Background mature polytypic B cells are present (blue).
Additional analysis for cytoplasmic CD3 and stem cell antigens shows that the brightest CD34+ cells (green) co-express cytoplasmic CD3 and CD117.
Additional analysis for myeloid and stem cell antigens shows that the CD34+, CD117+ cells (gold) co-express CD13 and HLA-DR.
Additional analysis for T-cell antigens shows that a subset of the CD45dim+ blasts (gold) is positive for CD7, and negative for surface CD3, CD4 and CD8. Lower right inset shows light scatter and CD45 analysis (FSC: forward scatter, SSC: side scatter).