A differential is performed on a bone marrow specimen obtained from a patient suspected of having CML in blast crisis. The results are as follows: 45% blasts, 13% metamyelocytes, 18% myelocytes, 10% promyelocytes, 8% bands, 2% segmented neutrophils, 1% pronormoblasts, 1% basophilic normoblasts, 1% polychromatophilic normoblasts, and 1% orthochromatophilic normoblasts. What is the M:E ratio?
A) 2:1
B) 24:1
C) 12:1
D) 15:1

Question

Quizplus · Accepted Answer

The M:E ratio is calculated by dividing the total myeloid (granulocytic and erythroid precursors) cells by the total erythroid cells. In this case, the myeloid cells include blasts, metamyelocytes, myelocytes, promyelocytes, bands, and segmented neutrophils, which sum to 94%. The erythroid cells include pronormoblasts, basophilic normoblasts, polychromatophilic normoblasts, and orthochromatophilic normoblasts, which sum to 4%. Therefore, the M:E ratio is 94:4, which simplifies to approximately 24:1.

A Differential Is Performed on a Bone Marrow Specimen Obtained