PMC4957483_01
Morphologic and immunohistochemical evaluation of diagnostic bone marrow aspirate and core biopsy. Diagnostic bone marrow aspirate (a and b, Wright-Giemsa, 600x) and biopsy (c, h & e, 200x) showing myeloid elements at all stages of maturation. The aspirate shows that blasts are not markedly increased and cells with cytology consistent with lymphoblasts are not readily apparent. Eosinophils (green arrows), basophils (arrowhead) and dwarf megakaryocytes (black arrows) are identified. Immunohistochemical staining of the bone marrow biopsy (100x) shows an expansion of CD34(subset) + TDT+ blasts (d and e, respectively) that form clusters. An expansion of CD3+ T-cells (f) without an expansion of CD19+ B-cells (g) is seen. In panel h, double staining of the biopsy (400x) shows that MECOM expressing cells (brown nuclear stain) are distinct from CD3+ T-cells (red membranous stain)
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Fig1
A bone marrow study revealed hypercellular marrow (>95 %) with increased myeloid cells at all stages of maturation, increased eosinophils, scattered basophils, few erythroid progenitors, so-called dwarf megakaryocytes, and sea-blue histiocytes (Fig. 1a-d). IHC of the bone marrow core biopsy confirmed these latter findings, showing individual and clusters of CD3+ TDT+ T lymphoblasts comprising ~10 % of overall cellularity and 20-30 % of cells in restricted areas (Fig. 1d-g). IHC for MECOM and CD3 was performed on the bone marrow core biopsy. Interestingly, the CD3+ population and the MECOM-overexpressing population were non-overlapping (Fig. 1h), indicating the T lymphoblastic transformation was independent of the acquisition of inv(3)(q21q26.2).