PMC4982915_01
A. Photomicrograph showing diagnostic specimen with lymphoblast morphology (Giemsa stain, 600X). B. Photomicrograph showing lineage switch specimen with monoblast morphology (Giemsa stain, 600X). C. At diagnosis, the CD45 dim blasts (yellow) were CD19+(shown), CD22+, CD34+, CD10- (shown), CD14- (shown), CD64- (shown), CD7- (shown) and TdT+(shown). D. With lineage shift, the blasts were CD19- (shown), CD34-, CD14+(shown), CD64+(shown), TdT- (shown), and CD7 partial (shown; see text for details).
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A complete blood count showed a white blood cell count (WBC) of 126 K/microL, hemoglobin of 16.7 g/dL, platelet count of 23 K/microL, and 47% circulating lymphoblasts (Fig. 1A). There was variable expression of the myeloid markers CD15 and CD33. The blasts were negative for CD3, CD10, MPO, and all other T-cell, myeloid, and monocytic markers evaluated, including CD14, CD64, and CD7 (Fig. 1C). A bone marrow evaluation following re-induction with the modified regimen (day +180) revealed 33% blasts, this time with monocytic features by morphology (Fig. 1B). These blasts were negative for CD19, CD10, CD24, and TdT, and expressed dim MPO, an immunophenotype consistent with monocytic blasts (Fig. 1D).