In the workup of an undifferentiated acute leukemia, which marker, demonstrable by nuclear staining, favors a lymphoid rather than a myeloid origin of the blasts?

• A Alpha-naphthyl butyrate esterase
• B Myeloperoxidase
• C CD34
• D Terminal deoxynucleotidyl transferase ✓

Explanation

TdT is a specialized DNA polymerase expressed in immature lymphoid precursors and absent from normal myeloid progenitors, so nuclear TdT positivity supports a lymphoblastic lineage. Myeloperoxidase marks myeloid blasts, nonspecific esterases mark monocytic cells, and CD34 is a pan-stem-cell marker seen in both lineages and therefore cannot discriminate between them.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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